Cant solve rough idle
Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
I did check it,on the 90 its non adjustable so it cant be adjusted, I replaced it about a year ago, right now the car will not even run, I replaced the pick up coil, unplugged the est wire and set timing, shut the car off plugged the est wire back in and now she will not run. I am going to take a break till this weekend and work on it then.
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
Ok she is up and running, my ignition module died on me, unfortunately I still have a rough idle. It seems worse when the hotter she gets. I am going to take another break from it now, I did do a short data log at idle I will post it when I get a chance.
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
I am new to data logging, by fuel trim what do you mean, I have aldldroid and it does not show fuel trim, it does show blm, int,bpw,blc,
at idle blm's stay at around 128, I know if it reads higher it is compensating for a lean mixture and lower is a rich mixture.
Last edited by eutu1984; Jul 25, 2015 at 09:46 PM.
Melting Slicks
Joined: Aug 2003
Posts: 3,395
Likes: 393
From: Lakeville MI
The idle appears to be steady based on the posted log. Roughness is not apparent in the data. Idle appears to be tracking target rpm +/- 25 rpm around 20 IAC counts. Fuel trims (BLM and INT are on the money).
I don't understand the complaint.
I don't understand the complaint.
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
Cant solve rough idle
Its very rough at idle, especially in gear even though the data looks good, it vibrates so bad in gear the vent cover almost pops off, it also vibrates in natural just not as bad.
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Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
Good luck
I had to use d grease because the corrosion in the connectors would keep coming back if I did not.
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
If I had your car, I would check and clean all the connectors and put some dielectric grease on them, put a timing light on all spark plug lines to make sure they are all firing, and then try simply adjust the distributor slightly each way and test drive , old school way. I have a slight cam feeling but it doesn't make too much vibration.
Good luck
I had to use d grease because the corrosion in the connectors would keep coming back if I did not.
Good luck
I had to use d grease because the corrosion in the connectors would keep coming back if I did not.
Team Owner
Joined: Jul 2004
Posts: 28,430
Likes: 3,279
From: Hartford WI
I did everything you mentioned already before you posted, I decided to run some Lucas gas treatment through it and it seemed to improve very slightly last weekend, It sat al week and when I started it it did not fire as fast as it normally does, and does not seem to be accelerating as smoothly, the injectors ohm at 15 cold 18 hot so there is no problem with the windings in the injectors so im starting to lean towards clogged fuel injectors or junk in my trunk (gas tank). When I have a chance I will pull the fuel filter. For now I think I will at least drive through a full tank of gas and see what happens.
Take the filter out and replace it if you haven't already. I think you can take the sock in the tank out but I wouldn't without ordering a new gasket and sock.
All that Lucas thing will do is lighten your wallet for sure. It may clean something but you don't know how much. Try cleaning a room blindfolded. Sure, you did clean something but how much is left, you don't know. I test it every 3 years. I read the "before and after" and I can see that some crud has built up or the basket filter might be dirty.
Team Owner
Joined: Jul 2004
Posts: 28,430
Likes: 3,279
From: Hartford WI
If I had your car, I would check and clean all the connectors and put some dielectric grease on them, put a timing light on all spark plug lines to make sure they are all firing, and then try simply adjust the distributor slightly each way and test drive , old school way. I have a slight cam feeling but it doesn't make too much vibration.
Good luck
I had to use d grease because the corrosion in the connectors would keep coming back if I did not.
Good luck
I had to use d grease because the corrosion in the connectors would keep coming back if I did not.
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
Advanced
Joined: Dec 2010
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What are the symptoms of your rough idle? Erratic misfires? does the engine speed surge and drop on its own? Any discoloration in the exhaust? Strange smells? Does the engine run properly when you're giving it throttle?
Team Owner
Joined: Jul 2004
Posts: 28,430
Likes: 3,279
From: Hartford WI
I have an inductive timing light that can check rpm based off spark signal. Can you use something like that to see whether each wire is getting about the same rpm based off signal in the wire?
You said you have good spark, correct firing order so maybe the fuel injectors are problematic? Is the fuel pressure correct throughout or just at idle?
You said you have good spark, correct firing order so maybe the fuel injectors are problematic? Is the fuel pressure correct throughout or just at idle?
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
Hello. I think I need a bit of clarification here. Does the engine idle fine in neutral?
What are the symptoms of your rough idle? Erratic misfires? does the engine speed surge and drop on its own? Any discoloration in the exhaust? Strange smells? Does the engine run properly when you're giving it throttle?
What are the symptoms of your rough idle? Erratic misfires? does the engine speed surge and drop on its own? Any discoloration in the exhaust? Strange smells? Does the engine run properly when you're giving it throttle?
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
I have an inductive timing light that can check rpm based off spark signal. Can you use something like that to see whether each wire is getting about the same rpm based off signal in the wire?
You said you have good spark, correct firing order so maybe the fuel injectors are problematic? Is the fuel pressure correct throughout or just at idle?
You said you have good spark, correct firing order so maybe the fuel injectors are problematic? Is the fuel pressure correct throughout or just at idle?
I have the inductive timing light and already did the check you sugest, last time I did the fuel pressure check I just did it at idle and it checked out good, this morning I removed the fuel filter and cut it open and it was very clean inside and its been on there about 3+ years, I will hook up the fuel pressure gage and tape to the window and take it for a quick run.
Thread Starter
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
Ok just came back from fuel pressure check, at idle 34, with vacuum line removed from regulator its 44, going down the road it holds around 34 untill I get on the gas then fuel pressure increases to the low 40's. With engine off the fuel pressure holds.
Last edited by eutu1984; Aug 2, 2015 at 04:45 PM. Reason: added ,
