Stumble, lean condition after work
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Joined: Aug 2004
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From: Houston Republic of Texas
Stumble, lean condition after work
I posted in general also.I have been desperately trying to get my car to run well, efficient. I had the engine overhauled in January and started replacing every thing I could see. We just replaced egr valve, fuel pressure regulator (stock ac delco)and injectors (denso #22lbs.)As soon as I fired it up, it has developed a significant stumble on acceleration and when scanned it is showing a lean condition (121 integrator ) Fuel pressure is correct, injectors all firing (noid light test) all pulsing exactly the same.
It has new Taylor wires, new AC Delco plugs,cap,rotor, coil, k&n air filter, new fuel pump, etc.
The tech who checked it says it may be a bent push rod or a broken valve spring and even mentioned a bad cam. I am hoping for some wisdom from the brilliant members here for help. As always, thank you all in advance.
It has new Taylor wires, new AC Delco plugs,cap,rotor, coil, k&n air filter, new fuel pump, etc.
The tech who checked it says it may be a bent push rod or a broken valve spring and even mentioned a bad cam. I am hoping for some wisdom from the brilliant members here for help. As always, thank you all in advance.
Melting Slicks
Joined: Jan 2002
Posts: 2,238
Likes: 4
From: Milan
I posted in general also.I have been desperately trying to get my car to run well, efficient. I had the engine overhauled in January and started replacing every thing I could see. We just replaced egr valve, fuel pressure regulator (stock ac delco)and injectors (denso #22lbs.)As soon as I fired it up, it has developed a significant stumble on acceleration and when scanned it is showing a lean condition (121 integrator ) Fuel pressure is correct, injectors all firing (noid light test) all pulsing exactly the same.
It has new Taylor wires, new AC Delco plugs,cap,rotor, coil, k&n air filter, new fuel pump, etc.
The tech who checked it says it may be a bent push rod or a broken valve spring and even mentioned a bad cam. I am hoping for some wisdom from the brilliant members here for help. As always, thank you all in advance.
It has new Taylor wires, new AC Delco plugs,cap,rotor, coil, k&n air filter, new fuel pump, etc.
The tech who checked it says it may be a bent push rod or a broken valve spring and even mentioned a bad cam. I am hoping for some wisdom from the brilliant members here for help. As always, thank you all in advance.
This does NOT means the car is actually run rich... this means that your ECM is slightly correcting a rich condition. You are at 14.7 . period.
This is not a fuel related (too much or too little fuel) problem (part throttle spaeaking).
WOT and heavy accelerations involving power enrichment routines in the chip are another story...
I don't see on your list the fuel filter.
-Beppe-
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Joined: Aug 2004
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From: Houston Republic of Texas
Fuel filter
That fuel filter was done also. As I noted: This started after the fuel pressure regulator, egr valve and injectors were changed. The BLM and integrator stuff is over my head. I'm trying to learn. I need help.
Le Mans Master
Joined: May 2005
Posts: 5,214
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From: Queensland, AUSTRALIA
Simply cause the BLM says its at 121 and its correcting what it thinks is a rich mix, doesnt mean it is correcting a rich mix. If the O2 sensor is buggered it could be telling the ECM its rich whether it is or not.
Have a look at the MAF sensor and see if the wire inside it is dirty.
Have a look at the MAF sensor and see if the wire inside it is dirty.
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Joined: Aug 2004
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From: Houston Republic of Texas
MAF Looks good
MAF Looks good, clean. My concern is the stumble on acceleration. Not to mention the doom and gloom the tech had for me about camshaft, valve spring or bent rod.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Get them to stick a wide band on it to check the integrity of the O2 sensor.
Check that the knock sensor is working as it should
Check the compression
CO test the coolant
Does it do this when its stone cold?
Does it do it in open loop and closed loop or just closed loop?
Check the TPS
Check the ignition control module
Check all the grounds
Check that the knock sensor is working as it should
Check the compression
CO test the coolant
Does it do this when its stone cold?
Does it do it in open loop and closed loop or just closed loop?
Check the TPS
Check the ignition control module
Check all the grounds
Team Owner
Joined: Feb 2006
Posts: 24,460
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From: sw Ohio
If the valvetrain was messed up it would be fairly obvious. It would sound somewhat lopey if anything was bent or worn out. Not so much the springs though, you'd probably have to take them out to find a broken one.
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Joined: Aug 2004
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From: Houston Republic of Texas
Answers
Get them to stick a wide band on it to check the integrity of the O2 sensor.
Check that the knock sensor is working as it should
Check the compression
CO test the coolant
Does it do this when its stone cold?
Does it do it in open loop and closed loop or just closed loop?
Check the TPS
Check the ignition control module
Check all the grounds
Check that the knock sensor is working as it should
Check the compression
CO test the coolant
Does it do this when its stone cold?
Does it do it in open loop and closed loop or just closed loop?
Check the TPS
Check the ignition control module
Check all the grounds
CO test coolant? No.
Yes it does it cold.
Both open and closed loop.
What check can I do on TPS?
aHH, Ignition control module. I can do that.
Grounds? Wow. From what I can tell there are hundreds of them.
Thanks for the leads. Truely.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
What do you mean "CO test coolant? No."? Are you saying you did it and you had no combustion gases in your coolant? Or are you saying you dont want to test it?
There are quite a few grounds, your car isnt working properly so check them all.
Put a volt meter on the TPS and make sure its within spec from closed throttle to wode open throttle. It should start at 0.54 volts and move smoothly up to somewhere around 4.5-5 volts at wide open throttle.
If its not at 0.54 volts when the throttle plates are closed then adjust it til it is. It should be no higher than 0.6 at closed throttle.
What about the knock sensor? Did you test that to be sure its working?
While youre at it, check the timing as well, it should be about 6* to 8* advanced with the ESC wire disconnected.
There are quite a few grounds, your car isnt working properly so check them all.
Put a volt meter on the TPS and make sure its within spec from closed throttle to wode open throttle. It should start at 0.54 volts and move smoothly up to somewhere around 4.5-5 volts at wide open throttle.
If its not at 0.54 volts when the throttle plates are closed then adjust it til it is. It should be no higher than 0.6 at closed throttle.
What about the knock sensor? Did you test that to be sure its working?
While youre at it, check the timing as well, it should be about 6* to 8* advanced with the ESC wire disconnected.
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Joined: Aug 2004
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From: Houston Republic of Texas
my mistake
(CO in coolant) I meant that I hadn't checked it yet. That would lead to a bad head gasket? As I noted, this thing started when I changed EGR, fuel pressure regulator and injectors.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Not always, it could mean a cracked head or cracked block.
The fact it only came up when you changed what you did may very well be coincidental, and you shouldnt leave anything to chance, everything you check as working correctly is another thing you can cross off the list as a possibility
The fact it only came up when you changed what you did may very well be coincidental, and you shouldnt leave anything to chance, everything you check as working correctly is another thing you can cross off the list as a possibility