Runs well cold, tip-in stumble, sluggish warm?

P

Powder

Member
Joined
Jan 2, 2003
I did a search for tip in problems and found nothing so I'm asking you guys for possible causes and solutions.
After changing turbo, inj(60's) MAF, GENII, Extender G, I've got a car that runs OK cold, driving easy, and starts running poorly after it warms up. Cruising at 45-50 the BL's start dropping from 128-130 to 110-112 and the car stumbles when you add throttle after coasting. Its really bad when starting out from a stop even though it seems to idle OK while stopped. Have not gone into boost with it running so poorly and its difficult to test while staying close to home with busy traffic most of the time. Any ideas on what to check? I don't know what to check, twist, adjust or just plain cuss at! Thanks for any help you might throw my way.
MLH
 
I would do a factory reset on the Gen II and reconfigure to your application.
Something may be corrupt.

The tune values can be reset to the factory defaults by holding the upper right keypad button for 15 seconds while powering up the unit.
When the default settings have been restored, the unit will display "All data Reset!"

If that does not work we can look at other options

Rick
 
Thanks for the response Rick. I've done that several times after learning I had the configuration settings wrong but I'm sure that part of the equation is correct now.
I'm currently using default settings on everything but the timing which I set at 19 through the RPM ranges.
The chip,for now, is at default settings because I don't have any voltage at the wire that taps into the parking light circuit. I plan to correct that later. Could that be a factor?
Also, I did bump the mainscale up 10% but lowered it while driving when the BL's started dropping while cruising. I don't know what the mainscale setting is as I just wanted to get the car home before it died. The int and BL's were sitting at 128 and 127 respectively while idleing before I shut it down. I hope its a tuning issue but what?
MLH
 
Hmmm, that some wierd sh!t.

Have you looked at the temp sensor reading?

Are all your gen II connections solderd?
 
I have the Caspers adapter. With what little I know about the electronics on these cars, it seems when the car warms up and goes to open loop(I assume) the ECM is getting a lean indication somewhere and adding fuel? I'm only guessing because the BL's start dropping from 127-130ish once it warms up and that's when I started backing the main scale down with no noticeable effect. It's difficult to make adjustments on the fly because of having to deal with traffic and not knowing what the car is going to do. I can't think of any adjustments I've missed to cause this. I don't know where to look next.
MLH
 
moving from 127 to 130 is normal. If it was like 90 or 150 then you might have something. Have you verified coolant sensor is working correctly. on the scanmaster its clt. (coolant)
 
I'm pretty confident the SM temp readings are correct showing 165-170 at easy cruise. The BL's are only reading 127-130 until the car warms up then they start dropping down to around 110. I lowered the mainscale from +10 to +1 while driving with no noticible effect. I would have kept lowering it but my trip through the hood was over so I just parked it.
One other possible variable, is I changed my air intake making it much shorter overall and had to lengthen the wiring harness to the MAF. It has a soldered extension and the connectors are tight and Mike felt the extra length should not affect anything. Could the dual electric fans be causing interference with the longer MAF harness when they kick on?
Also, the LS1(3.5") MAF connects to the 4" turbo inlet via a 6" long 90 degree adapter. I clamped the daylights out of it so I don't think there are any air leaks, but another variable. I think I made the mistake of changing too many components at the same time. I have to believe the problem is between the ECM, chip, GEN II, and MAF.
Thanks again for you help.
MLH
 
I'm pretty confident the SM temp readings are correct showing 165-170 at easy cruise. The BL's are only reading 127-130 until the car warms up then they start dropping down to around 110. I lowered the mainscale from +10 to +1 while driving with no noticible effect. I would have kept lowering it but my trip through the hood was over so I just parked it.
Click to expand...

Got it, temp sens is good.
Try going -10 on the mainscale. Take a ride and see if blm comes up.
I doubt this is the stumble problem but you should be able to get bl's up.



One other possible variable, is I changed my air intake making it much shorter overall and had to lengthen the wiring harness to the MAF. It has a soldered extension and the connectors are tight and Mike felt the extra length should not affect anything. Could the dual electric fans be causing interference with the longer MAF harness when they kick on?
Click to expand...

I don't see why it would. Although anything is possible.


Also, the LS1(3.5") MAF connects to the 4" turbo inlet via a 6" long 90 degree adapter. I clamped the daylights out of it so I don't think there are any air leaks, but another variable. I think I made the mistake of changing too many components at the same time. I have to believe the problem is between the ECM, chip, GEN II, and MAF.
Click to expand...

Can you snap a pic of the set up? Also mabye its time to read the plugs and see what they tell us. Some pics of those would help out too. Also how old is coilpack and module? Thats something else to look at. If spark is weak or droping out, the car will be rich, hence 110 BLM. The other thing is a sticky injector. Does FP hold?
 
Your logic is very good but most of those parts have been replaced with less than 1K miles on them. This is a 63K miles garage queen that I just work on 95% of the time.
I'm going to back the mainscale down to "0" and take a quick test ride while I have a break in the weather and traffic and see if that helps. I'll let you know what happens.
Also, we have digital cameras but don't have any means to post on this board that I'm aware of. I'd love to email a couple to you to get your feedback if you don't mind.
MLH
 
Just finished a short drive and nothing has improved. The BL's while under light load (25-30mph/coasting to a stop) kept going down as I lowered the mainscale. When I got to -4.0 the BL's were at 100 until I stopped and the car idled at 135. Before adjusting, the car was idleing at +/_128. The car feels like its on 3 cylinders from a stop until you get to just below 2K rpm's.
I don't understand how the mainscale can lean the idle but add fuel to cruise with the same adjusment. Could I have a bad component like the GEN II or chip?
MLH
 
Cam sensor is new. I haven't pulled any plugs yet but why would they work fine until the car warms up? I'll pull some tomorrow nite just to make sure I'm not overlooking something. The motor idles very well at all times, just goes way rich at cruise and runs crappy when it reaches operating temp.
MLH. By the way, I really appreciate you hanging with me on this. Hopefully we're also solving someone elses future problem. There's a solution somewhere because this was a great running car until I put all these new parts on.
 
Somthing may work fine until it becomes heat soaked. Unpluging the cam sensor and it will throw the ecm in limp mode. The car will no longer depend on any of the sensors. If the miss clears up, we have a bad sensor somewhere. Does not nessesarily mean it's the cam sensor, I was thinking more like crank sensor.

I think if we get the miss figured out, I'm thinking bl's will level out too.
 
I dropped the main scale to -10 and the car idled so rough I dropped it back to "0" and didn't drive it. Next I unplugged the cam sensor and realized the car had to be running. When I plugged it back in and started the car which was at operating temp by now, it ran like normal. Now I'm really scared because it fixed itself after I fiddled with the cam sensor wiring.
The car now runs at 128 bl at idle and real close, 127-128 at 50mph. This tells me all parts are essentially good and the tune is close enough from a driveability standpoint. Now I just have to find out what was causing it so it doesn't become an intermittent problem.
Thanks again for all your help on this. The car is a little less complex than it was a week ago.:cool:
MLH
 
Could have been a bad conection at the plug? Hmmm, very interesting.
Well at least something happen. Always glad to help fellow TB'rs.

Cheers.......:D

Rick
 
You must log in or register to reply here.

Similar threads

M
Surge after Cold Start
Replies
9
Views
775
mkyledoyle
M
R
Rough idle when engine cold
2 3
Replies
43
Views
5K
Boostrules
B
8
Used Alky control parts needed
Replies
4
Views
878
313badbuick
3
8
Weird issue Stalling Sputtering when warm
Replies
10
Views
2K
84ttype
8
Mr. Michael
Stumble & die
Replies
4
Views
941
Mr. Michael
Mr. Michael
Top