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View Full Version : Help with backfiring and IDing parts


Mark Johnson
11-14-2005, 10:44 PM
I'll warn you up front, this is going to be rather long ;-). Bottom line is, I have bought an 1987 Grand National from someone who only had it for a year. He knew it was modified (and it is), but didn't know exactly what was done to her. So I need to discover what I have, so I can go about setting it up properly. I bought the car back in August and I've been browsing the web, reviewing the materials here and reading "Grand National Performance and Restoration Tips". The car has been modified and I need to find out what has been done already, so I can verify that everything is matched, or go about upgrading the parts that are'nt. That's the short version. If you want to take a look at what I have, I have set up a quick web site at http://ptmark.zapto.org/GrandNational/EVILAYR.html. The images are large, but if you download them and zoom in you can see most of the details and part numbers.

So, here's my intro. My name is Mark Johnson, also known as MoParmAARk or PTMark around the Internet. I've been into Mopars for the last 10 years and have become fairly comfortable with the V8/points/Carb performance. The world of computers is where I make my living, but modifying a car with computer controlled systems and a turbo is all new to me. I live in Pasadena Maryland, just South of Baltimore, and I'm 48 years old. I've wanted a GN since 1987, when my wife spotted one at the Buick dealer while we were looking for a new car, with a $10,000 budget! Needless to say, we weren't driving out of there in a GN for $10k ;-).

Here's the car, she's a 1987 Grand National. The intercooler appears to be an Action Fabrication 15 row stock location intercooler. The Turbo is not stock, the closest thing I have found so far is the Precision GT TSM-70. The Turbine side is marked Precision, M3, A, G1, 270/89. The compressor side has very few markings. In a rectangle near the output side are the numbers 12 and 01 each in a circle. On the underside of the output snout is a hand scribed 63. The intake side is 4 inches O.D. and the output side is 3 inches O.D.. The boost is adjustable and has been set at 20 lbs. The injectors have a Blue ring on them and are marked D31658A. The chip in the computer has a Silver label marked 1605 and DRL. It had a "hotwire" kit installed for the fuel pump, I don't know if the pump has been upgraded. It has an ACCUFAB adjustable fuel regulator, with a Speed Unlimited fuel pressure gauge under the hood. It has a cone air filter. I believe it has a 3 inch down pipe with a hollowed out cat to a single muffler and 2 tailpipes exiting behind the tires, all stainless. Inside we have a Scanmaster version 2.0, a boost gauge and a temp gauge that's not hooked up yet.

How she runs. When I first got her, I think she ran really great. The second day I had her, she went sideways when I floored it and the turbo kicked in (scared the crap out of me!). Then......one day on the way to work I decided to floor it and it backfired, I let out and hit it again and it backfired again. The rest of the day I took it easy and it ran fine, just no stomping the gas. However, on the way home she shut off and would not restart. After towing it home (by the way, where do you put a tow rope on one of these, spent 20 minutes beating the dent out of the bottom of the bumper when I got home). After a little research I came across a "Hotwire" kit and noticed the fuse on the back of the alternator, went out to the garage and sure enough the fuse was blown. I replaced the fuse and she's been running since (at least 300 miles). Problem is now the backfire problem is consistant. Partial throttle acceleration is phenominal, at 30 mph she'll squeal the tires for 50 feet when the boost kicks in. But if you floor it, she backfires.The fuel pressure was set at 42 or so, I dropped it with no change, when I raised it to 48 it seemed to help. I also noticed that the boot on the turbo intake was torn, at first I didn't think it could be a problem, then I realised the MAF (I think) doesn't see that air so it could be a problem. Oh yea, the Scanmaster sees retard when ever the turbo is under a lot of boost. Around 7 or 8 without backfiring, floored it will hit the high 20s and 30s, but I don't know if the knock sensor can tell the difference between knock and backfire. Without boost there is no retard, mild boost yeilds either little or no retard. The O2 readings are erratic at idle and in the high 700s and low 800s under throttle. Which way is rich, higher or lower?

Well if you're still reading this, thanks for hanging in there. My progress will be slow, as I have way too many irons in the fire. I hope to get a laptop in a swap for a desktop and the TurboLink software for Christmas, that should help. Anyway, any tips, thoughts or advice is appreciated and if you can tell me anything about what I have, that would be great. I've been told Anderson Performance in Baltimore is really good, any one dealt with them? I try to do it all myself, but I would love to have this car live up to it's potential.

Keller
11-14-2005, 11:07 PM
First, welcome! :bye:

Your turbo isn't stock, but is a far cry form a TSM-70. Its a lot closer to a stock turbo. Not sure what the injectors are, but we have some references on this site to look them up. The Mark Jackson intercooler is a good piece. The downpipe is a widened stock type, as it is still attached to a stock elbow from the turbo.

Your boost should not exceed 15 PSI on pump gas. Otherwise, you will hurt something. If you don't know how to adjust it, seek assistance.

If you need some help in your area, you might want to talk to http://www.anderson-performance.com/

Mark Johnson
11-14-2005, 11:26 PM
Thanks Keller, I'll back the boost off. Do I need to run race gas to run more boost? The injector section shows a Lucas injector that looks like mine, but the part number is different. I went to the Lucas site and they have one that looks like mine and the part number is closer, but not the same. My understanding is that the turbo, injectors, chip, exhaust and intercooler should be sized to work together. My problem is I don't know what size anything is ;-). Sounds like backing the boost off is something I should do anyway, I use the car as a sunny weather commuter. Thanks!

kenmosher
11-15-2005, 01:15 AM
Injectors look to be 009s (42.5#) ...hard to tell.

The turbo could be a TE45 ... http://www.gnttype.org/techarea/pictureguides/turboguide/TE45.html

That might be pushing those injectors to feed that turbo. The O2 volts sound reasonable at the lower boost levels (see the Quick reference guide http://www.gnttype.org/maint/quickref.html) ... higher O2s are generally richer.

Keller
11-15-2005, 01:46 AM
Injectors look to be 009s (42.5#) ...hard to tell.
Rings may be blue instead of green...

Mark Johnson
11-15-2005, 05:18 PM
Thanks, I've found a 4" to 3" silicone coupler to replace the torn rubber plumbing supply fitting that was on the turbo. I called Anderson Performance in Baltimore and they will look the car over for about $200. When I get the coupler tomorrow I'll lower the boost and see how she runs. Then I'll call Anderson and set an appointment to have them go through the car.

bmackinnon
11-17-2005, 05:18 PM
Mark,
Scott Keller and Ken Mosher are the most knowledgable guys imo on this forum, and i'm no genious. That said, I find it rather surprising that they wouldn't be screaming about "20-30" degs of retard along with a loud backfire. :shock: Sounds to me like a 'lean pop'.... not a good thing as every one could be your last, at least until you change the resulting blown head gasket. Another possibility that nobody mentioned is weak coil pack(s). I had the backfire under boost (~18-19 psi) problem without a lean condition and it took me forever to figure out what the problem was. Ended up being a marginal coil pack. Replaced both and never backfired again. But in your case, with massive retard, and moderate retard even under lite boost, I suspect a lean condition that needs to be addressed fervently. Don't let it backfire!!!

Ken? Scott? That rite??

kenmosher
11-17-2005, 06:01 PM
Sounds right to me ... I guess my base assumption was the retard was related to the backfire (often times that'll send the sensor NUTS!)

It's pretty obvious that the lean condition is the immediate concern ... and as you've pointed out, there are many other possible contributors.

Keller
11-17-2005, 06:47 PM
I find it rather surprising that they wouldn't be screaming about "20-30" degs of retard along with a loud backfire.

The numbers all sort of ran together in that post. After awhile I wasn't sure if the 20-30 was knock counts or PSI boost. Regardless, either is too much. I am surprised something hasn't given up the ghost yet.

Lean or not, 20+ psi on pump gas with reasonable timing just isn't the way to keep your headgaskets solid. The O2 numbers cited sounded OK, and I don't think more fuel would fix it. Turning down the boost is the sane option.

Sounds like this guy has a few wrenches, and has touched a few cars before. Once he reads up on which knobs to turn which way, and what levels to read with what, I'm sure he'll take to getting this ride tuned up and down the road quick!

As always, with a TR that is used, but new to you, the "Spring Cleaning", plus the usual gauges and a good check with a scan tool is a must. As they age, there are more chances of finding problems.

Mark Johnson
11-19-2005, 11:23 PM
UPDATE: Well, Last night I pulled the intercooler shroud and scoop and did a little cutting, hammering and fitting, then after replacing the 4 screws that were holding it on, I added the 7 that were missing, should stop the tapping noise it was making. Then tonight I installed the new 4" to 3" reducer and finished re-installing the intake. I added 5 turns to the wastegate adjustment (trying to go from 20 lbs. to 15 lbs of boost) and backed the fuel pressure back to 40. A quick run around the block ( about 4 miles) showed 17 lbs of boost and the backfiring was almost gone at WOT. Back to the garage, I added 3 more turns and took her out again. Now she was showing 15 lbs of boost, at WOT the 02 was in the 780's and the knock retard was in the single digits (vast improvement), but she was SLOW!! Back at the garage I bumped the fuel pressure back up to 45, she ran worse! A little more backfire and 02's in the low 800s, knock retard 11-13 ish at WOT. Back at the garage I dropped the fuel pressure to 38. This time much better acceleration (not as good as I was getting with 20 lbs of boost), no backfire, 02's in the 770s and knock retard at 7.

I decided to call it a night. This wasn't the carefully documented, scanmaster reading, analize each change type of test I had been planning. But the car is now very driveable and I think the next step is to schedule a visit to Anderson Performance after Thanksgiving to get a thorough going over before I proceed much further. I'm going to print up some data sheets with places to fill in the date, time, typical changes, all Scanmaster readings and driving immpressions. I'll keep these on a clip board in the car so I can easily track all my changes and results.

Thanks everyone for the suggestions, as you can see, I used or tried almost all of them. I'll keep you posted on my progress.

Keller
11-20-2005, 04:31 AM
Mark,

Very good tuning. The target should be roughly 15 PSI and O2s of rougly 780 and knock of 0 or close to it. No idea whose chip you have. More boost makes more power, but if it makes knocking and backfiring, that means problems. If you want to run 20 (or more) PSI on the street, plan on running race fuel or an alcohol system in the future.

Mark Johnson
11-20-2005, 09:04 PM
Thank, Keller, I miss the power she had at 20 lbs ;-), but I want to have Anderson evaluate what I have before I do any more tweaking. The alcohol injection definately sounds like something I'd like to look into. I want to drive this car often enough that racegas is not a practicle answer for me. I'm hoping there is a good amount of torque left in tuning, so I can have the tire shreading accelleration I had before and keep the boost down. Thanks again, and I'll keep you posted.

Mark Johnson
12-04-2005, 03:07 PM
Update: Anderson Performance looked my car over and here's what they reported:

Parts I have that are fine:
Hotwire kit, internal fuel pump
ATR 3" Dual crossflow exhaust w/cat
63 4" inlet Turbo
1 1/2 intercooler, stock location
Accufab adjustable regulator
Scanmaster
3" K&N filter

Parts I have, that he recommends I upgrade:
37# injectors (like I was told here, too small for the Turbo)
He's recommending 50# @ $48 each or 65# @ $55 each.
He says with the 65s I shouldn't need to upgrade again
(at least for a while ;-))
Stock chip (Isn't supporting the Turbo or the 37# injectors)
He has someone who cuctom burns his chips for $75. after I
choose the injectors he can get one made for me.
3' downpipe, stock elbow
The stock elbow is restrictive, he said I might want to look at
getting a 3" downpipe w/3" elbow.
Type 2 coil pack
He feels the original is the best, he can get me one for $75.

Right now my plan is to wait for financial approval from Lynn (my darling
wife who supports my hobby), then order the 65# injectors, coil pack and
appropriate chip from Anderson. After I install these parts the car should run
much better! Then we shoot for phase 2, get financial approval for a Dyno tune from Anderson, they said it should run $200-$275. Phase 3 will probably be alcohol injection, so I can turn the boost back up a little. Then get the A/C fixed before Summer.

Questions:
When they say its a 63 Turbo, are they talking about the diameter of the compressor wheel, the A/R ratio of the compressor, the A/R ratio of the turbine or the diameterof the turbine wheel?

What do you think of this proposed combo?

Any guesses as to the ET/MPH capability of this configuration?

Thanks again for your help, I'll keep you posted.

Keller
12-04-2005, 04:27 PM
For the injectors, I agree on going with the 65# units. He's likely referring to the 60# MotoTron injectors, sometimes called 65# units.

Also, you may need a dual fuel pump setup. One pump will not support your horsepower target.

The turbo scenario is clearer now. Here is a picture of a TE62 vs. stock. http://www.gnttype.org/techarea/pictureguides/turboguide/TE62vsstock.html The TE62 is very close to what you have. The nomenclature of TR turbos can be very confusing, but in this case it makes some sense. The 63 is the compressor size in milimeters. See http://www.gnttype.org/techarea/pictureguides/turboguide/turbos.html , http://www.gnttype.org/techarea/turbo/turboupdate.html , and http://www.gnttype.org/techarea/turbo/turbowheels.html

For a downpipe, I would highly suggest a Terry Houston downpipe. Possibly a 3.5" model vs. the more common 3" for your application. http://www.gnttype.org/techarea/pictureguides/downpipes/THDP.html Not sure what specific pipe Billy was suggesting, but I'd run that by him and see what he thinks.

As far as power/ET...with alcohol, decent injectors and pumps to supply them, the right torque converter for the combo (I don't recall this being mentioned), and proper tuning, this could be a 700-750 HP+ setup easily.

Mark Johnson
12-05-2005, 12:29 PM
Also, you may need a dual fuel pump setup. One pump will not support your horsepower target.

What do you recommend? I found a fuel pump Voltage booster in the car's console. of course that make me a little suspicious of its condition ;-).


The nomenclature of TR turbos can be very confusing, but in this case it makes some sense. The 63 is the compressor size in milimeters.

Thanks, that helped clear up a lot.

For a downpipe, I would highly suggest a Terry Houston downpipe. Possibly a 3.5" model vs. the more common 3" for your application. Not sure what specific pipe Billy was suggesting, but I'd run that by him and see what he thinks.

Will do, he sort of brought it up as an afterthought. He basically gave me a list of what I had, with stars by the coil pack, injectors and chip. His Dad said those were items I should upgrade. I went back out to the shop and asked him what he recommended I upgrade to. After reviewing the 3 items above he threw in that I might want to upgrade the downpipe because of the elbow.

As far as power/ET...with alcohol, decent injectors and pumps to supply them, the right torque converter for the combo (I don't recall this being mentioned), and proper tuning, this could be a 700-750 HP+ setup easily.

He didn't say anything about the TC, but you're right it needs to be addressed. I also did not mention alcohol injection to him at this time.

Sounds like I can stick with my plan, I'll just bring up the alcohol injection and ask for TC recommendations when he does the Dyno tune. I'm going to need to wait a while for the Alky and TC ($$$), so hopefully the car will run fairly well after the tune. Being on a budget sucks! ;-).

Keller
12-05-2005, 07:09 PM
Volt Booster can provide a good improvement, but will not supplant the volume of a 2nd pump. I'd suggest a modified stock fuel pump hanger and a 2nd pump. Might be worth replacing the one that is there while you are at it, just in case.

Sounds like they are in agreement about some sort of downpipe upgrade.

Mark Johnson
12-16-2005, 11:12 PM
Well I ordered the 65# injectors, the stock coil pack and module and a custom chip from Anderson Performance today. I also went out and picked up all the parts for the "Spring Cleaning". Bill thinks the Alcohol Injection would be too much for the stock bottom end, so since I'm not looking to build a full race car, I think I'll pass on the alcohol. I'll get all of this together in the next few weeks, then take her to Anderson for a Dyno tune in February or March. I'll probably just keep an eye out for a used 3.5" downpipe for now, not only are they hard to find, but they seem to cost a lot more than I suspected. Anyway, I'll keep you posted on my progress.

Thanks again for all of your help!

Mark Johnson
01-07-2006, 11:18 PM
Well, it's great to have this forum back. I went down to pick up my injectors, coil pack, ignition module and chip at Anderson's, due to a better chip being ordered and my not asking for an estimate on the ignition module (I thought it came with the coil pack), my preparation for a $500 bill was not enough to prepare me for the $770 bill. Bill jr. was not there so I called him later in the week (his Dad misplaced the itemized bill). The chip I ended up with, a Commander chip has a handful of adjustable settings including a "check engine" shift light feature! That was $50 more than estimated, but I think well worth it. The other discrection was the ignition module at $185. I went out to the garage and rummaged through the spare parts box and found the damaged coil pack and sure enough it had a module attached. For $185 I decided to check it out first. The coil pack also had a missing connector, so I had t go back anyway. Bill gave me a new coil and credited me for the module, so I was breathing easier ;-).

Finally got a chance to install the parts last weekend, luckily years of experience have prepared me for the fact that the simplest proceedures can take all day. I had disassembled my spare intake and injectors so I knew it was going to take some time to coax each injector out without bending or breaking anything. Everything went pretty well, of course between GM and the aftermarket I had almost every standard and metric tool I own under the hood by mid day ;-). I replaced a couple of O-rings on the fuel lines and found a few other odds and ends that needed attention. The coil pack was initially a concern because the old type II pack had no markings on it, and I've worked on enough cars not to assume I know the numbers of the cylinders. Luckily the injector plugs are marked and the cylinders are numbered conventionally, so it was a peice of cake putting everything back together. The chip went in without a problem and the single wire it requires (for programming) was a breeze.

Sooooo... Add a quart of oil, air up the leaky front tire and climb in. She turns over a few times (empty fuel rail) and fires right up. The idle feels much better, overall the car feels much more driveable. It seems to spool up slower and not accellerate as hard, but this is without any tuning. Of course I came down with this killer cold and have been off work ever since and have'nt driven it since. I'm dying to ge out there, I'm hoping the TPS was knocked out of adjustment when the bracket was removed (this would explain the lack of accelleration). I also noticed the aftermarket boost gage doesn't budge while the stock gage is showing 5-8 psi, then it jumps in and tops out at 20 psi (after I adjusted the wastegate to 15 psi a few weeks ago). No backfire, the highest knock I saw at WOT was 2, I can't wait to tune this thing.

I want to check the TPS and then go over the boost lines and make sure none of them are leaking. Set the fuel pressure and then go out and collect some numbers with my Scanmaster. Thanks everyone, I'll keep you posted.

onefastcar
01-08-2006, 07:38 PM
Sounds like things are goin good keep us posted.:cheers:

NOTACARLO
01-10-2006, 12:03 AM
$75 chip burn??? Sounds like you will get to know Mr. Armstrong. If it is Red's, you will be a happy camper. Congrats on your purchase and welcome................


Welcome to the Dark Side

Mark Johnson
01-21-2006, 08:54 PM
OK I adjusted the TV cable and set the TPS, at this point I discovered I wasn't able to get good numbers on the Scanmaster for the TPS. Eventually I pulled the hose off the throttle body and noticed it wasn't opening up fully. It turned out the TV cable was routed in such a way it would not adjust itself and was restricting the travel of the throttle cable, after an hour or so I figgured this out and by pulling the TV cable straight and opening the throttle all the way the TV cable adjusted and the TPS numbers were right where they belong (after a little more tweaking). Of course this was after destroying one TPS by opening the slots too much! Luckily the P.O. threw in a spare TPS.

Time to pick up my buddy and go to our "test area". The first run left 2 tracks of fresh rubber a little over 300 feet long (yes I went back and paced it off ;-)). Worth noting, my buddy and I add 650 pounds to the car, we're working on that problem separately ;-). The second run Dennis was able to hook (I warmed the tires up) and the Scanmaster hit 99 mph before he backed out of it (anyone know if the Scanmaster reads over 99?). I went back today to get some images and the trucks had blown most of the rubber away. So after a few shots, I went ahead and laid down a fresh set! Should have them on my web page soon.

Now a question, my IAC readings are 0. I backed the idle down to 500 rpm with the IAC disconnected and when I reconnected it and restarted it idled back up to 750, but still no IAC readings. The car was warm, no A/C per the instructions, any ideas? Thanks again for all the help.