Banned
Rage!!
Hi guys.
Back again with an annoying off idle stumble. Car wants to stall, has no power then like a switch is thrown It up and goes like a cut snake.
Here's what I've done.
New o2 sensors.
New coils.
New fuel filter.
New leads.
New spark plugs.
Cleaned the throttle body
cleaned the fuel tank and fuel pump sock. (wasn't that grotty at all).
When it plays up it spits and farts and feels like it wants to die in the arse, then I'll get a back fire off one bank (has happend on both banks) and off it goes like there's nothing wrong.
All thats been done recently is I fit up a whole new exhaust system. New cats, new Extractors and 2.5" twin system.
There are no codes showing on the scan tool. The fuel trims seem fine. The ignition advance is fine. The TPS and IAT is fine.
It almost feels like a car with a carby that's too big. Anyone that's been there knows what I mean.
The old boy took it for a run and said it feels like the idle is too low. Which makes no sense obviously.
But could the TPS or idle control be up the shit?
383ci HTV2300 blown LS1!!
only one way to find out. i changed my TPS not long ago and it made it run alot better. also have you had yours tuned? maybe its time for a maffless tune!!Originally Posted by soop
want to see more then a typical commodore fitted with an exhuast, then check my thread out... link broken cuase i dont own a tuff car, i just made it up...
Banned
Yeah, going fuggin maffless. Had enough of this prick of a thing.
Will change the TPS too. Can't hurt at this point hey?
383ci HTV2300 blown LS1!!
yeah i got mine fron Holden $280 just for the TPS. when i pulled my old one off, it had all this white stuff around it?? must of been a bit dirty, but doesnt hurt to slap a new one in.
want to see more then a typical commodore fitted with an exhuast, then check my thread out... link broken cuase i dont own a tuff car, i just made it up...
Who wants chowder?
Just tune the sucker mate, won't know yourself.
Banned
Yeah I am going to. Could even be the MAF giving up. I did run the same filter for like 12months!
I can get a TPS off ebay brand new for about $40....
Getting a car tuned that has a pre-existing issue will lead to disappointment. Find the problem first. I know you feel like you've tried everything, but theres still at least one more sensor that could cause what you are experiencing and that would be the MAF. Clean it (properly, and gently) and give it another go. Failing that, try a friends. There are so many around from people getting MAFless tunes that you won't have any problems trying to source one.
Banned
Yeah I've cleaned the MAF.
Might pinch dads. His car has no fuel now anyway LOL.
Now that I think about it, it kinda makes sense.
Car drives like a dog whilst moving slowly, but like I say once you boot it int the guts and you get some RPM up it goes grea,. and no issue cruising at 100km/h. Possibly an issue with low airspeed over the MAF?
its the air intake temp sensor getting heat soak from the extracters. happened to my ss, ran for months and once the weather warmed up the same prob happened. my car was also tuned which exageratted the prob as it was running 22* advance. fitted up an otr and relocated the iat sensor and the prob never appeared again.
took a fair while loggin it on vcm suite to get it to show up as the day i took it to my tuner was cold n overcast. it was pulling all the timing in one hit. would only happen if the car was sitting in the hot sun for a while or the car was idleing for over 30 seconds. once up to speed the natural airflow cools the sensor and all is good in the world. so id say get an otr and tune and relocate the sensor.
if you want to test my theory pull the sensor housing out of the intake duct and run it ove the radiator cover to the hole in the corner behind the left headlight and pop it into one foe the slots and run around for a few days. just make sure you block off the hole in the intake. when i did this it still had the problem but very rearly which to me indicated that heatsoak was the prob.
Banned
Interesting.
The issue only arose once fitted the extractors.I'll give it a crack I guess. I did not that sitting in the car port on a warm day the IAT sensor read 54c after a drive.
Ambient would have only been 30 at max.
Thanks for the input.
This is a pretty common issue with poorly tuned MAFless cars, but wouldn't be an issue with a standard tuned MAF car. The IAT is designed to correct fueling / pull spark as temperature rises, this is its purpose.
Banned
Yeah it didn't do anything anyway.
I've tried that. Tried the MAF. Didn't work.
I really reckon its something to do with the idle control. It still spins up hard going 1st to 2nd. So it's not lacking power.
Years ago my car did exactly this, and I tried everything to fix it. In the end the only solution for me was to put the car in full open loop (disable o2 sensors) and dial the VE table in perfectly. No amount of new o2 sensors could fix the problem.
This was visible for me in the EFILive logs with STFT's slowly creeping up at the lights, and while creeping up the car would start to rock and buck. Once they maxed out, they'd return to normal and the car would idle perfectly for about 15 seconds. Then the STFT's would start to creep up again, repeating the problem.
Banned
Ahh that sounds like a prick of an idea.
What causes it?
If I knew, I would have fixed it instead of disabling the o2 sensors
Banned
Haha, Is it a PCM issue?
If so, might be easier to get a mail order Mafless tune and replace the PCM.
Other thing I've thought about, could the little idle control stepper motor in the TB be playing up?
I changed the PCM and loom with mine too, still didnt fix the problem, but it might be the problem with yours, hard to say.
Usually if the IAC is playing up you'll have larger swings in RPM, stalling and idle hang. Certainly worth trying another one though, but you may need to do a PCM reset to relearn its position. Non-genuines are available on eBay pretty cheap.
Exhaust Guru
Check your plugs, you have to remove them to fit the extractors and it is very common to crack a plug.
Banned
Yeah I've seen them cheap. Might give it a crack.
That Fuel trim issue sounds bizarre, possessed car!
The car really feels like its going to stall at times, untill I boot it in the guts, I've seen the tacho fluctuate a couple hundred rpm while cruising at times. But its sort of to random to really say.
For a few bucks I might as well try it. Will probably have to get a bloody torx bit too while I'm at it. Shitty bloody things they are. Edit- Just bought one for $45, see how we go. I'll be stoked if this fixes it. Can't see it being a drastic issue because the car pulls like a 13yr old school boy otherwise.
Abba - They're new plugs since I fitted the extractors, as are the leads.
Last edited by soop; 02-01-2011 at 12:59 PM.
Exhaust Guru
Did the issue start after you did the exhaust? How long after that did you do the plugs?
Banned
Probably a week after I did the exhaust the problem started. I put new O2's in at the same time as I fitted the exhaust.
I replaced the leads and plugs about a week after the fact, and it made no difference.
Banned
Want to hear something really funny?
Found the problem...
Buggered battery clamp, is loose a goose. Wont tighten up so im up for a $2 Batter clamp. Tested it by changing mine with dads. Wallah, dads car gets aids and mine is good....
Its ALWAYS the fuggin $2 part isn't it...
Who wants chowder?
lol, always the simple things.
At least you've fixed it.
Banned
Yeah, but what a stupid bloody thing to miss!!!!
Thinking to hard about shit. Though it felt the world like something was dying in the arse. But nope, just low voltage at low RPM...
Any wonder the car up and went all of a sudden, probably when the alternator had enough RPM to take over.
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