PDA

View Full Version : Need to Eliminate Cold Start Rough Idle


87ntrdr
06-16-2006, 10:43 AM
Since I bought my '87 GN back in '04, I have had to correct many things. So far I've replaced a valve cover, a mainseal, all hoses, a fuel filter, installed a cold air intake, gauges, and vacuum brake conversion. But there remains one pesky, annoying, dreadful little problem: on a cold start, the car does not idle well.
I've already done a forum search and I know that this problem seems to be prevalent. What I don't know is the different ways that I can track it down. I have plenty of tools at my disposal, just not diagnostic tools. I have a code checker; the car is not throwing any codes.
We didn't notice the car having problems with an idle until I had the cold air intake installed. The car went into the Buick dealership where they checked for low counts on the IAC, which were then supposedly corrected. There is a bit of underdrive noise from the bottom of the engine, and I have a wonderfully harmonious lifter knock. I have not replaced the fuel injectors, though I have run enough STP through them to kill a city.

Questions:
1. Where is a good place to start tracking this problem?
2. Is there a diagnostic tool that I can buy that will help me track it down? I have a laptop but it is a Mac.
3. Is there anyone with experience with these cars in the Northern VA / Charlottesville area?

- W.G.

87geeinn
06-16-2006, 01:28 PM
First off, these cars have a lopey sort of idle especially if you are using a stock chip or a chip that does not have open loop idle programmed into it. I think several chips--I'm 100% positive Eric's TurboTweak does--have open loop idle programmed into it. The car will run richer, but closed loop idle was an emissions thing. Mine idles smooth as glass even when warming up with a TurboTweak chip.

www.turbotweak.com

Also, there are several diagnostic tools available. Perhaps, the easiest and most user friendly would be the Scanmaster. You can find it here:

http://www.fullthrottlespeed.com/items~Cc~SCAN~iTpStatus~0~Tp~~Bc~.htm

For pete's sake, don't take your TR to the dealership to check IAC counts. With a diagnostic tool you can check IAC counts and a lot more. It will pay for itself.


Keep reading everything you can on this site and you'll start to grasp things. Getting all the bugs worked out on these cars takes a long time sometimes. Something as foreign as setting the TPS and IAC counts may seem foreign at first, but becomes second nature after you do it for awhile.

JHensberry
06-16-2006, 01:33 PM
First, if you plan on keeping the car and learning about it, get a scan tool, with one you could prob immediately go to the right place.
Second, try unplugging the orange ECM wire for 10 seconds, then plug in, let it get warmed up and take it for a 15 minute drive. Lets the ECM relearn some numbers, sometimes helps, sometimes not.
There is an IAC/TPS reset on the website that you can do yourself with a multimeter and a paper clip, good thing to learn anyway.
Did you get a clt temp gauge, has the sensor been replaced yet?
Does it go away when warmed up?
What thermostat do you have?
It could be related to IAC/CLT/TPS, I'd say try the reset and take it from there, Joseph.

87ntrdr
06-23-2006, 01:15 PM
Yeah, the rough idle goes away when the car is warmed up. i have a water temp gauge installed. It warms up to about 190 or so; going up to around 200 on a 95ºF day. I don't know what particular kind of thermostat I have; I have not replaced it, though I have a Stant replacement at home. I will try doing the ECM reset this weekend while I am at home fixing the power windows and doors; although I'm fairly sure that since I have had the battery disconnected several times the ECM has been reset several times and the problem has not gone away. I may have to purchase a diagnostic tool, though I have a Scan Tool already. Thanks for the point towards TurboTweak.

- Will

87ntrdr
06-25-2006, 08:35 AM
So this weekend I switched from the chip that I bought the car with to a chip that the car came with; from a Casper's Electronics chip to a Kenne Bell chip that I have. I havent' really had a chance to test out the differences but the idle did definitely improve. It still sounds like the car might have a mistiming or something like that, but this is an improvement. I did notice that my boost does not come on as early with this chip, and I'm wondering if this other chip was not as good or just was messing with an already overly messed with car.

- Will

turbobuicksix
06-29-2006, 07:05 AM
Best thing you could do is get rid of those old chips and get a turbotweak as mentioned before.My motor also was a shaker when cold but the TT chip totally fixed it.

Keller
06-29-2006, 04:06 PM
Kenne Bell stopped chip development about when these cars were built. There are many better ones.

You need to get a scan tool. There is a brief overview of them in our scan tool section.

You need to check coil resistance, etc. There may be problems. A scan tool and ohm meter will go a long way toward helping your analysis.

zpd307
07-17-2006, 04:33 AM
when i first got my we4, it was in a sorry state of neglect. i had to start from step one. anyway, when i did finally get it running it had a very poor idle. it would go up and down. basically it would sputter and almost die and then catch itself and rev way up. it only did this until it warmed up. the two things that i remeber doing that corrected it was changed the o2 sensor and i took out the iac motor and clened the hell out of it and the passages with carb cleaner. i think that read somewhere that a dirty iac would cause that problem. i was amazed at how dirty the iac motor and passages were. just be careful of the gasket as it is probably old and brittle. i broke mine and couldnt find just the gasket anywhere. i hope this helps.

Roadrunner88
07-17-2006, 07:15 AM
i was amazed at how dirty the iac motor and passages were. just be careful of the gasket as it is probably old and brittle. i broke mine and couldnt find just the gasket anywhere. i hope this helps.

Where did you eventually find one?
Did you fabricate one yourself?