idle issue, what else should I look into?
idle issue, what else should I look into? 2000 trans am, auto, 2.73 rear, stock cam
I did a torque converter (gm55 trailblazer i6 converter), long tube headers, EGR, AIR delete recently.
I bought the EGR and AIR delete kit, sent the computer off to efi performance, they did a tune and deleted the rear o2 sensors.
I forget what I gapped the plugs to, maybe .045? not sure if thats my problem or not. Ive sprayed with carb cleaner to check for leaks and cant find any. IAC is newer.
I pull into a parking lot and the idle surges like crazy while coasting, im not sure if its in 2nd gear or 1st when that happens (I almost feel like its stuck in 2nd and is fighting the idle?). The car has died befor when it does this. It also has some on and off idle issues at stop lights, if I put it in nuetral its fine. Im using new o2 sensors, the good brand denso I beleive, off a corvette with the longer harness (as far as I know, maybe I got a bad one?). I cleaned the throttle body, new plug wires, tr55 plugs.
I have a little ALDL obd2 reader but not sure what to look for. Car didnt have this problem befor all the work and I cant seem to find anything that stands out. When I deleted the AIR I put the vac hose on a coilpack bolt stud and unplugged the pigtail, spraying with carb cleaner the engine doesnt rev up. Where else should I look? Can anything transmission related cause this?
Ive searched on here and nothing seems to stand out. Now Im thinking its an O2 sensor, but it doesnt do it all the time.
I did a torque converter (gm55 trailblazer i6 converter), long tube headers, EGR, AIR delete recently.
I bought the EGR and AIR delete kit, sent the computer off to efi performance, they did a tune and deleted the rear o2 sensors.
I forget what I gapped the plugs to, maybe .045? not sure if thats my problem or not. Ive sprayed with carb cleaner to check for leaks and cant find any. IAC is newer.
I pull into a parking lot and the idle surges like crazy while coasting, im not sure if its in 2nd gear or 1st when that happens (I almost feel like its stuck in 2nd and is fighting the idle?). The car has died befor when it does this. It also has some on and off idle issues at stop lights, if I put it in nuetral its fine. Im using new o2 sensors, the good brand denso I beleive, off a corvette with the longer harness (as far as I know, maybe I got a bad one?). I cleaned the throttle body, new plug wires, tr55 plugs.
I have a little ALDL obd2 reader but not sure what to look for. Car didnt have this problem befor all the work and I cant seem to find anything that stands out. When I deleted the AIR I put the vac hose on a coilpack bolt stud and unplugged the pigtail, spraying with carb cleaner the engine doesnt rev up. Where else should I look? Can anything transmission related cause this?
Ive searched on here and nothing seems to stand out. Now Im thinking its an O2 sensor, but it doesnt do it all the time.
Last edited by trilkb; Aug 3, 2018 at 01:32 PM.
I talked to them, they say theres 1000 cars out there with this tune and its well ironed out, and of course the guys wifes car has the same tune and runs perfect. Sometimes I think thats just a line to feed a customer.
I guess comparing o2 readings might tell me something? To me it seems like a closed loop problem. I can even spray around the PCV valve and nothing changes.
I guess comparing o2 readings might tell me something? To me it seems like a closed loop problem. I can even spray around the PCV valve and nothing changes.
Thanks, I will check. Hopefully my ALDL reader with the program "torque" can tell me these values. On a motorcycle today though so maybe tonight when I get home ill fool around with it.
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like others mentioned on checking for vac leaks, check especially around the egr and air pump since that was what were removed. also check around the vac ports around the throttlebody.
Its odd, I thought that if you sprayed around the suspected areas with carb cleaner that it will suck in the carb cleaner and the engine will change rpm, usually higher rpm. Im not getting any of that anywhere. Maybe I should try giving it some throttle and doing it?
What people fail to realize is when you put a stall in the car it can mess up the idle. I’ve seen it several times. Why? Because I know in my car, my yank was 10lbs lighter than my stock converter. When you take that rotating weight away then theres less stored energy so the idle can become unstable. What is causing it?
1) idle adaptives may be too aggressive.
2) because you put headers your afr isn’t going to be quite right anymore. A mail order tuner will sometimes rely on the computer to correct itself. Not a good way to do. I like my trims to be less than 3% and if you have large swings that will cause it.
3) timing tables may not be smoothed enough with each other.
All in all the likely culprit is the lighter weight convertor.
also the down shifting of the trans can cause it to go into a tizzy. There’s a lot more to all this than I’m explaining. Something else I’ve done is reduce the downshift pressure multiplier because sometimes under no or little throttle the downshift will be too abrupt. You may not even feel it but it affects the engine when consign to a stop. In most of the tables I’ve seen the stock multiplier at 0% throttle is 25% more pressure. I reduce it to 12 or 15%
1) idle adaptives may be too aggressive.
2) because you put headers your afr isn’t going to be quite right anymore. A mail order tuner will sometimes rely on the computer to correct itself. Not a good way to do. I like my trims to be less than 3% and if you have large swings that will cause it.
3) timing tables may not be smoothed enough with each other.
All in all the likely culprit is the lighter weight convertor.
also the down shifting of the trans can cause it to go into a tizzy. There’s a lot more to all this than I’m explaining. Something else I’ve done is reduce the downshift pressure multiplier because sometimes under no or little throttle the downshift will be too abrupt. You may not even feel it but it affects the engine when consign to a stop. In most of the tables I’ve seen the stock multiplier at 0% throttle is 25% more pressure. I reduce it to 12 or 15%
Last edited by Kfxguy; Aug 3, 2018 at 11:06 AM.
Generally it will, if it's big enough leak and you hit right on it. I usually find engines misfire from the additional "fuel" but depends on the situation.
That car would run on a stock tune. I dont know the place that did the mail order tune but t would be hard to mess up a tune for those mods, but everyone make mistakes. Spraying brake cleaner on anything else doesnt hardly work on new motors, I have seen more times I can count people do that and ind nothing and we hook up a smoke machine and its leaking like crazy. You will either need to data log the car or have someone else look at the tune to rule that out. The data log is the best option. If you want a second opinion on the tune just pay for return shipping and send us the pcm and we will look at for you.
Yes the maf and throttle body has been cleaned quite a few times.
The idle issue isnt that bad, its the weird surge I get every so often where the idle jumps from 300-900 while coasting. Like ill pull into my bank, I have to come to a stop to deal with the curb, pop the gas to get up and over it and then coast down a hill and thats when it happens. Or if im in a parking lot ill give it a little gas and coast and it will do it. So its actually a 1st gear issue, because if I coast in 2nd its fine.At stop lights it could be smoother but the car isn't dieing or anything.
Also I didnt put a crazy stall in, I used a trailblazer GM55 converter, so possibly thats whats messing it up? The main reason for me sending it to them was to get the rear 02's and EGR/AIR deleted.
The tune was tunedbyfrost, which is now Efiperformance. Im not saying they are bad and Im definitely not saying its their fault. Every car is different and I beleive if 1000 cars are using the same tune I am, then its likely something I just havent found, perhaps the gm55 converter is making the car different then the other 1000 though.
Good to know about the brake clean/carb clean method not being a good indicator. That is actually the best information Ive got yet because now I know there is something wrong that im doing.
The idle issue isnt that bad, its the weird surge I get every so often where the idle jumps from 300-900 while coasting. Like ill pull into my bank, I have to come to a stop to deal with the curb, pop the gas to get up and over it and then coast down a hill and thats when it happens. Or if im in a parking lot ill give it a little gas and coast and it will do it. So its actually a 1st gear issue, because if I coast in 2nd its fine.At stop lights it could be smoother but the car isn't dieing or anything.
Also I didnt put a crazy stall in, I used a trailblazer GM55 converter, so possibly thats whats messing it up? The main reason for me sending it to them was to get the rear 02's and EGR/AIR deleted.
The tune was tunedbyfrost, which is now Efiperformance. Im not saying they are bad and Im definitely not saying its their fault. Every car is different and I beleive if 1000 cars are using the same tune I am, then its likely something I just havent found, perhaps the gm55 converter is making the car different then the other 1000 though.
Good to know about the brake clean/carb clean method not being a good indicator. That is actually the best information Ive got yet because now I know there is something wrong that im doing.
Last edited by trilkb; Aug 3, 2018 at 11:35 AM.
That car would run on a stock tune. I dont know the place that did the mail order tune but t would be hard to mess up a tune for those mods, but everyone make mistakes. Spraying brake cleaner on anything else doesnt hardly work on new motors, I have seen more times I can count people do that and ind nothing and we hook up a smoke machine and its leaking like crazy. You will either need to data log the car or have someone else look at the tune to rule that out. The data log is the best option. If you want a second opinion on the tune just pay for return shipping and send us the pcm and we will look at for you.
that’s funny. My ls1 gto ran fine on the stock tune with headers and an air intake. But when I put a yank 3400 convertor in it, it started surging. So I have to disagree. Some cars my get by, but as someone above said, all cars are just a little different. But hey, whatever. Just my personal experience. I wholeheartedly believe if you drop 10lbs rotating mass then it’s very likely your going to experience idle instability.
that’s funny. My ls1 gto ran fine on the stock tune with headers and an air intake. But when I put a yank 3400 convertor in it, it started surging. So I have to disagree. Some cars my get by, but as someone above said, all cars are just a little different. But hey, whatever. Just my personal experience. I wholeheartedly believe if you drop 10lbs rotating mass then it’s very likely your going to experience idle instability.
where did you get the surge and how did the car surge?
when I was coming to a stop. Sometimes would do it it. Sometimes not. The rpms would go up and down. Sometimes die. Had a Silverado brought to me that was tuned by someone else. He had a stall put in it was the only difference. Did the same thing.
Thats kind of what im dealing with! The only odd thing is that this gm55 converter is nothing special, I dont even notice any difference in how it drives. The idle at stop lights is like 100-200rpm up and down and not very crazy, but the surge it does like you explained and its enough that it has stalled the car befor.
TECH Junkie
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that’s funny. My ls1 gto ran fine on the stock tune with headers and an air intake. But when I put a yank 3400 convertor in it, it started surging. So I have to disagree. Some cars my get by, but as someone above said, all cars are just a little different. But hey, whatever. Just my personal experience. I wholeheartedly believe if you drop 10lbs rotating mass then it’s very likely your going to experience idle instability.
I emailed the tuner asking if they were certain they saw my note about the gm55 converter and havent heard back, im sure they are just plain sick of me....and why would they want to deal with a paying customer after they already received my money? So I get it.
