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Special K
11-13-2005, 09:41 PM
I just got my first 87 GN last week. There have been some modifications from stock, but I am still green identifying all the different mods since this is my first Buick. There is a problem when you get off the line. When you are at a stand still and then punch it, it hesitates, doesn't stall though, power comes back and when the turbo spins up, then every things fine.

It idles around 750-850 and I have not done any "spring cleaning" yet. I also have an old Monitor 2000 that I just found out how to use after some trial and error. Can I diagnose this problem with the tools I have, or do I also need TurboLink?

Any help diagnosing this would be greatly appreciated.

-k

kenmosher
11-13-2005, 10:59 PM
Do the spring cleaning and do the IAC reset and TPS setting:

http://www.gnttype.org/techarea/maintenance/TPS.html

http://www.gnttype.org/techarea/faq/IACreset.html

Many times these simple things will do wonders!

Special K
11-13-2005, 11:06 PM
Thanks. I will try that and see what happens!

-k

Special K
11-20-2005, 10:05 PM
Well, I followed the IAC reset procedures, and the first problem I ran into was the car would not idle at 500 +-50 RPM. The car would stall and I could only get it to idle around 650. 500 seemed way to low. Has anyone else had a problem running the car at 500?

Moving on to the TPS, I found that at idle, it was set to .86 volts. So I got the sensor in the .40 range, and at WOT I could not for the life of me get it to anything above 4.27. Then I set the TPS to .46, and at WOT it would not go above 4.31. I tried for over an hour to get the low and high within range, so I settled for .46 and 4.31. After I tightened the set screws, I started the car the TPS at idle changed to .48. Is that normal? Since I couldn't get the TPS within range, is the TPS faulty (or just me :))?

I ran the car around the block and now it stalls when you go into corners and at stoplights. I have to torque brake it most of the time. The car idles funny too. It drops RPM a couple hundred sometimes, not really surging though. The hesitation is still there at the low end when it does idle properly. Still have not changed plugs, wires, etc.

Thanks for any input.

-k

turbojd
11-20-2005, 10:21 PM
When you were setting the tps for WOT, the floor mat wasn't in the way was it? If you still can't get the tps in WOT range try and oblong the adjusting holes a little bit for more adjusting range.

Special K
11-20-2005, 10:39 PM
The car mat was out when i was testing. I also found that WOT at the pedal was the same at the linkage hitting bottom. So after I found that out, then I was just setting WOT while I was under the hood.

I can't figure out how my adjustments can get the TPS right in both ranges. I only have .06 volts to play with according to the TPS guidelines. So how can I set it to .40-.46 and still get the top end to +4.55 volts? I guess a better question would be, it seems that both top and bottom ranges are dependant on the movement (up and down), so how can I ever achieve +4.55 volts when the bottom is already set to .46 on the low and the top is at 4.31?

I have no knowledge of the how the TPS works. So if someone can shed some light on how it works that would be great.

-k

Keller
11-21-2005, 12:15 AM
TPS range is dependant on the swing of the peg on the throttle mechanism against the TPS. So, the TPS has to be mounted further toward the front of the car to get higher/lower numbers. To get it further forward, it may need slight modifications. The mounting slots may need to be modified slightly.

turbojd
11-21-2005, 08:05 AM
Loosen tps screws slightly, pull the tps forward towards the radiator a little, move the tps nose up or down a little until you have .40-.46 at idle, check tps at WOT if not in range of 4.55-4.65, then the tps has to get pulled forward more towards radiator when adjusting, if you cannot get that high a reading then the tps slots will have to be modified to give you enough room to pull the tps forward to get the WOT readings of 4.55-4.65. Once you get WOT readings recheck idle settings again, it may take a little playing with.

Special K
11-21-2005, 09:52 AM
Setting the idle according to the online help above shows running the idle running around 500 RPM? Anyone have problems running their car at 500 +- 50 RPM? It just sounds wrong to my ears to have the car running that low.

-k

Keller
11-21-2005, 11:14 AM
That is only with the IAC unplugged. It doesn't run like that all the time. These cars usually idle at 750 or so. Its commanded in the chip. Read the directions carefully.

87geeinn
11-21-2005, 07:24 PM
Just for everyone's info: I purchased the TPS voltage booster plug in play kit and I like it for it's convenience factor. It is handy because all you have to do is move the TPS sensor around until the little green LED light lights up. Plus, it boosts the voltage at around 60% throttle so you don't have to worry about adjusting for WOT. I simply like it because I have to adjust mine quite often lately due to modifications being done currently on my GN.

Keller
11-21-2005, 08:17 PM
Waste of money, IMHO. :tdown: Just a good modification & adjustment would keep you from spending your money.

JHensberry
11-22-2005, 09:13 AM
I agree with Scott. I must admit I did have one along time ago. The proper TPS settings will do the same thing and save you all that money. There are plenty of products that claim to help but really dont. Just next time, try to do some research and get feedback. Thanks, Joseph.

Special K
11-23-2005, 02:52 AM
Is there any way to tell what the prom in the ECU is set to for RPM? You can change the RPM by setting the idle set screw, but shouldn't the RPM match what the prom is set to?

I have about 4 spare proms I can change, but how can I tell what the setting are for each prom?

-k

Keller
11-23-2005, 09:54 AM
A scan tool will show this number. Both the programmed idle, and actual idle.

Special K
11-24-2005, 09:33 PM
After about 2 hours working on the TPS, I finally got it to specs. It took not only modifying the slots of the TPS, but also the plastic grooves the TPS rests against the metal housing. They were the two plastic crescent shapes near the backside of the metal leaver. Once those were shaved, the TPS could move more freely to the front of the car, and that's how I got it to specs.

The car idles now around 750. The hesitation is still there. What usually happens is that when you accelerate, the engine bogs down (sometimes to the point where it could stall), and then picks up.

I would have to say the adjustments to the TPS helped. I am going to replace the spark plugs and wires tomorrow. Any suggestions on which brand to buy and what to set the gap to?

-k

Keller
11-24-2005, 10:38 PM
This may indicate a fuel system issue. (i.e. dirty injectors, weak pump, low pump voltage, etc.)

Plug info noted via http://www.gnttype.org/forums/showthread.php?t=3456

Always check the site first! And post questions in the appropriate area. :nono:

stizkidz
11-25-2005, 02:11 AM
With an OTC 2000 scan tool... How can I read my WOT TPS numbers? I do not feel comfortable putting the pedal to the floor with the motor on, can this be achieved with the motor off?

Keller
11-25-2005, 02:23 AM
Not going to WOT with the motor on will be a big damper on your 1/4 mile times... :loll:

Sure. Just turn the key on (motor off), and the the OTC turned on and running. Then, right foot to the floor like you mean it! Then, read the TPS volts.

Make sure your mat isn't interfering with pedal travel.

Special K
11-25-2005, 12:42 PM
Just found something this morning...a loose vacuum hose. It wasn't connected to the big canister coffee can underneath the K&N air filter. It has one side going to PCV and the other TO FUEL. What is this thing?

There is a little hesitation, but not that much anymore. I would say 80% is gone away, but I'll see what happens after I change the spark plugs, wires, fuel filter, etc and what happens when I run it around the block.

-k

Keller
11-25-2005, 03:37 PM
The cannister is used to filter the fuel fumes from the tank. In your case, it was an open vacuum line, and having it connected was better than having it open.

stizkidz
11-29-2005, 02:52 AM
I don't see how it is even possible to adjust the TPS and IAC together to maintain correct settings... Basically, you are only adjusting the TPS to read to spec at idle and at WOT. However, adjusting the TPS also affects IAC settings. So how are you supposed to only adjust 1 thing and still have 3 things read within spec? It seems like at least one reading will always be a little out of spec.

Keller
11-29-2005, 10:21 AM
It is possible, grasshopper. :) Patience... Its just a matter of achieving balance.

Fortunately, it doesn't need to be done but once, normally. People like us are the only ones that fiddle with our cars enough (and keep them long enough) to even care to do it more than the time they roll off the line.

stizkidz
11-30-2005, 02:26 AM
Idle TPS is at 0.40, WOT TPS is at 4.38. I know this is not totally within spec but my IAC readings are within the 20-40 range also. Should I really mess with it until I can get WOT to 4.40 or should I just leave it alone cause it's as good as it's gonna get?

Special K
12-04-2005, 10:18 AM
I tried for over 3 hours to get the TPS set right and I couldn't. It wasn't until I modified the housing of the TPS that I get it into spec.

I did notice something about the hesitation when I move the TPS while the car is running at idle. When you move the TPS while the car is at idle, does anyone else have problems? Is this normal? Should I even be worried about the hesitation while moving the TPS at idle?

kenmosher
12-04-2005, 12:41 PM
Normal ... what you do when you move it at idle, is you are telling the ECM that the throttle is opening, but it really isn't.

BTW, you should probably set the TPS with the KEY ON/ENGINE OFF ... not with the motor running.

Special K
12-04-2005, 10:00 PM
I did set the TPS with the Key on and the Engine off. What I found was that when I did that, the TPS was .40/4.65, but when I turned the engine on and checked the settings again, it was .36/??? (didn't look at it when it was WOT).

But i did two different methods too. So perhaps that is why they are different, but have not confirmed that. I got the .40/4.65 with a volt meter plugged into the backside of the TPS. When the engine was on, I used my OTC Monitor 2000 and got .36 at idle. Don't know why the OTC would tell a different voltage.

Keller
12-05-2005, 01:03 AM
Key on or engine on will always be a bit different. Tune for that situation.

buddiiee
12-06-2005, 07:25 AM
special k.. you wanted to know what plugs and wires? ac delcos at 35 thousandths..and go with msd wires.