Rugh Idle and miss

D

darkred87T

Active Member
Joined
Oct 27, 2003
I have an '87' Regal Turbo T. The car has a fresh engine rebuild and has always had a rough idle (before and after rebuild). As I bring up the RPM (in park), I get a stumble that stays no matter how high RPM goes. Also, it always smells rich and I get a visible vapor out the tail pipes. I tried new injectors, replaced sensors, and checked for vacuum leaks. It seems to run a little better but still has this underlying problem. Does this sound familiar? Any suggestions? Thanks
 
That sounds like my car too. I am going to reolace the cam sensor here in a few days and let you know what happens.:)
 
Thanks, Actually, I can hear the cam sensor unit hitting the cap sometimes. I have another cam sensor that I can try as well (the whole unit) but I am hesitant to replace it because I'm not sure how to set it.
 
I can't remember but i think You get a tool that should automaticly alighn the sensor for you. Or it a pice of plastic, but there is something.
 
I learned that you can unplug the cam sensor while the car is running and it will go into a "Batch Fueling Mode" (or something) which means the car will stay running and you can drive it to determine if bypassing it made a difference. Unfortunately, I did this and the car still has a stumble with the sensor unplugged.

However, I got the information on how to set the cam sensor on www.gnttype.org. It doens't sound bad, You bring the Engine to 25 degrees above TDC and you can use a volt meter to position it.
 
I pulled the chip out and started the car today to see if it would run any different without it. The hesitation cleared up but the idle was high with "service engine soon" light flickering. When I reinstalled the chip it went back to it's old ways of rough slow idle with the "off idle" hesitation. Is this how the car would normally run without the chip? Does this mean I have a bad sensor?
 
Have you tried unplugging the mass air meter and see if idle improves or try borrowing a known good mass air from a friends car? Has to be a one from a turbo car.

Sounds like classic bad mass air meter to me.
 
Yeah, I upgraded to an LS1 MAF and translator and it still runs the same. Next chance I get, I'll post numbers. I might try a new TPS.
 
Just an update. I recently installed a new AIC motor (made no difference of course). Every time I try to set the AIC counts they eventually fall back down to 0 at idle.
 
cam sensor

Hi!
Don't waste time with a cam sensor; that's not your trouble.If something is wacking away inside the sensor, change it, otherwise no.I would guess a tps or maf might help, but I'm leaning towards lean mixture as the culprit. What are block learn and integrator numbers looking like? The ecm knows, so pay attention.O2 and crosscounts are also important, but lead the above parameters. These computers have a slow data transmission rate, so get ready to wait for data. Good luck!
Dale
 
Close your throttle blade by adjusting the screw on top of the TB. The rpms will want to come down when you do this. This is normal..then they will come back up. You'll also need to recal the TPS when you move that screw. Get your IAC's in park, hot, in the 20's. Trust me.. close the blade. Lets get this worked out first.. then work on other issues.

Idle problems are typically IAC related. Yours is improperly set. Also the chip has the idle set at 650 RPM's.. thats typically very low as well.

Look at the bottom of the text screen, you'll see PGM Idle 650

Post back.
 
Every time we adjust the throttle blade to get the IACs in the 20s, they find their way back to 0 over time. It acts and looks like a vacuum leak but we've checked every vacuum line countless times. Sprayed starting fluid around the intake and common leak areas. Nothing.

We've replaced:
- coil pack and module (not new, but off of my car so I know it works)
- TPS
- IAC
- Plugs, wires
- MAF (LS1 w/ translator)
- O2 sensor
- Multiple chips, 2 different ECMs
- turbo (GT3255) - the old one was puking a ton of oil into the intake tract

The car runs crappy from the second you turn the key - it's not really a closed-loop thing. It idles stupid fast and misses terribly (not just one cylinder, though) when cold. It idles so fast I'm afraid to drop it into gear (I'm driving the car while the title issues get sorted out with my Caddy). When it gets into closed loop it runs better - the idle comes under control somewhat but it hunts a bit.

In closed loop there is a bit of a stumble off idle, but not as bad as before he replaced the TPS and IAC (it would stall before, now it just hesitates a bit). Part throttle it's decent, and WOT is good too. Doesn't smoke. What is strange is the knock sensor will light up at really low boost levels. Not a ton of knock, green and into the yellow sometimes starting at 5-7 PSI. I don't know if it's real or not. If you stay in the throttle, the knock doesn't increase - it's just an initial reaction to stabbing the throttle. Motor mounts and trans mount are new.

I still think it's getting air from somewhere but I can't figure out where.

Any advice would be appreciated. I talked my brother into buying this car and I feel bad it's become a source of frustration for him.

Jim
 
I would try goin through everything on the intake side looking for a leak. I spent 3 weeks looking for mine, also drive the acr for a few miles, it may eed to relearn.
 
Before I spend anymore money on what's not the problem, I'm taking it to this Dynotech place in Manville, NJ . I heard they are good.
 
You must log in or register to reply here.

Similar threads

B
Miss at idle, miss at cruising speed.
2
Replies
23
Views
2K
TurboBuRick
T
Paulmac201
Speedometer and Odometer Problems
Replies
2
Views
240
KC87
K
B
Can't get engine to idle
Replies
11
Views
1K
boosted84
B
M
Stalls only during burnout
2
Replies
20
Views
1K
Chuck Leeper
Chuck Leeper
P
Manifold Vacuum has always been low....what to do?
Replies
2
Views
209
TIMINATOR
TIMINATOR
Top