Hesitation worse after cleaning EGR

[James806]

3.1 v6 Grand Am GT no mods. Code was P0401 EGR flow insufficient.

I had my Check engine light on for a while. So I read all the posts about EGR carbon buildup. Occasionally (off and on) there was a ticking sound from the front of the engine AND at the same time hesitation on accelaration.

So I had the EGR passages cleaned and the code/light cleared and off. But the ticking and hesitation got much worse and much more frequent (various times daily). It happens both at cold startup and after warmup.

No other codes

What else could be the problem? PCV, O2 sensor?

I am almost positive it is the emissions system since it got worse immediatly after cleaning EGR passages. Mechanics claim they cannot find anything wrong.

For PCV... When you take off the pcv valve with the engine running isn't it supposed to try to stall? Mine has no effect. I checked for pcv vacuum, it has it.

For O2 sensor? How do you test?

[sunrunner_pei]

Does the EGR valve show signs of excessive heat? If so, check for a clogged catalytic converter. I wish I could help you more. :(

[James806]

No signs of heat damage. I need to take it in for vehicle inspection this weekend. Maybe if it fails that will tell me more. Not sure what to do now. I am replacing the pcv valve this afternoon since they are so cheap. But since it was getting vacuum I don't really think thats it. Fuel filter changed recently, so can't be that.

I still think it has something to do with the EGR valve. Maybe it is sticking open now?? What do you think?

If the valve is stuck open, what are the symptoms?

What other components are there to the digital EGR system on my Grand Am?

[SonicTron]

Unplug your battery reset computer?

[James806]

The computer has been cleared and reset by the mechanic using the OBDII Scan. No new codes found.

Besides disconnecting the battery does not reset the computer on '96 and newer. OBDII retains the codes in the computer. Only way to reset is with scan tool.

[GA1999]

The only way to test an EGR valve is to take it off your intake, hook it up to a hand vacuum pump and see if the diaphragm moves freely inside. I'll bet by cleaning the the EGR valve it might have gotten damaged.

[James806]

The EGR valve on my car is "Digital". There is not diaphram to get damaged. It either checks out that it works or doesn't work using the OBDII scanner.

The EGR valve itself still checks out ok.

We cleaned the EGR passages.

[cocobob]

I had similar problem symptoms but with a P1374 3X ref. circuit code. The sluggishness was very âpparent between idling and 2000 rpm and poor gas mileage. I replaced the coils. One of them had improper impedance at the primary - it was still working but inefficiently. The symptoms were intermittent also, sometimes at cold and /or at hot temp. What mileage is on your ignition wires - check for arcing at night under hood. Check ignition module also.

[James806]

I replaced them about 3 years ago. Can't remember why. But the code it registered at that time is how we found it. No codes now.

I have also looked for sparking at night. None that I could see.

In the mean time I had a recall last year about the ignition harness. They installed a relay to prevent a fire in the ignition. Could that be related?

[James806]

I think I found the problem.

I had already checked for arching at night but I realized after reading your post that the problem was not occurring at that exact moment. So tonight when the car started acting up I pulled it into my garage and shut the door/turned lights off. Shazam! I found arching.

How do I figure out exactly which wires/plugs/coils are shorting?

The front three wires were lit up like a christmas tree. Only one plug as far as I could tell. Is there a way to test whether the coils are shorting as well? Can the one plug be causing all three front wires to short?

Any help would be appreciated!

Thanks

[cocobob]

If you gotta chang 1 or more wires by all means replace the complete set to match resistance load. Might as well change plugs if they are approaching 100K (60,000 miles) also.
Your firewall side plugs are hard to get to. As opposed to my 97' I believe your 96 has a hinged engine mount to hinge fwd the engine to get to them. Otherwise remove the ignition coil and module and the evap solonoid switch and you can reach the plugs with 2 short extensions and a hinged socket handle. Do 1 wire and plug at a time. Do not overtighten the coil paks on re-installation. One question I have is why your old wires arc intermittently - might be the coil paks that are arcing - check for carbon deposits on coils.

Cheers

[James806]

I checked the coils for carbon but found nothing.

That is why I was asking how to check the coils. I only have 20K miles on these coils, plugs, & wires.

What could be the cause of the short.

Question on arching... I did not see arching as in externally jumping from one wire to another, or to the housing. I saw the electricity flowing inside the wires. Sometimes when I touched the wires it would "activate" where I was touching. I could not feel the current but could see it. Is that normal? Does that mean a short or do you normally see the electricty flowing???

[cocobob]

James - I don't believe you should see arcing. I have heard that some new wires are pure crap depending on the brand. Pull one off and measure resistance on wire - it should be below 25,000 ohms. The impedance will increase as arcing continues so a low reading does not mean they are goo either. Make sure that the arcing wires are not near or touching any of the 3 electrical connections or harnesses going to the ignition module.

Individual DIS coils are tested in essentially the same way as epoxy-filled (square-type) ignition coils. First, isolate the coil pack by disconnecting all the leads. Set the ohmmeter in the low range, and recalibrate if necessary. Connect the ohmmeter leads across the coil’s primary terminals, and compare the primary resistance reading (the 2 connections below the coil paks) to specifications (typically less than 2 ohms). Then connect the ohmmeter leads across the coils’ secondary terminals (the 2 connections going to opposite cycle cylinder plugs)and compare the secondary resistance reading to specifications (typically 6,000-30,000 ohms). If readings are outside the specified range, the coil is defective and needs to be replaced.

If measuring the secondary resistance of a DIS coil is difficult because of the coil’s location, try removing the wires from the spark plugs and measure secondary resistance through the plug wires rather than at the secondary terminals on the coils. Just remember to add in a maximum of 8,000 ohms of resistance per foot for the plug wires.

It can also be the ignition module acting up or its connections.

[James806]

Well the mechanic said it is not any of the coils, plugs, or wires.

Since the problem is intermittant he thinks it is the lifter spring. Does what I describe sound like the lifters to ya'll?

I don't know anything about the lifters. How much would fixing one be.

He wants $90 just to open it up and see. At least another $50 to fix.

Is there another post with a detailed description of the lifter problems that seem to be mentioned so much on this forum.

[cocobob]

If he thinks a lifter spring then I would presume the related valve's performance would also be affected and that would be easily and cheaply diagnosed with a $15 vacumm gauge reading of the manifold. To help understand what the gauge says while diagnosing try : http://users.bigpond.net.au/ergoff/vac1.htm
I am not a mechanic but my hobby has been inboard boat engines (volvo and 88' GM350 5.7L -carburated and with points (no EFI or ECM) where we rely alot on vacumm guage readings.

As for my 97 GA, it has over 224K km so I just bought an Equus 3100 scan tool for $120 us to keep up with failling parts and problems. The garages out here in Canada charge between $65 -$80 just for a scan reading - no Autozone.

Keep us posted - you got me curious.

[James806]

You are right. The reason he 'THINKS' it is the valve spring is the compression on cylinders 3&5 are low. We have checked the codes (not at autozone) several times. There are no codes coming up.

I am still concerned that it is something to do with the EGR system since they cleaned it and the next day the ticking and hesitation was much worse. Would clearing the EGR passages allow a lifter problem to become worse or more pronounced?

Not trying to blame the mechanic. Just wondering why the day after they work on it I have all these problems. I trusted them before this... now I'm not sure.

I hate to spend all this money on a wild goose chase. My car only has 70K miles on it. Is it normal to have these types of problems with so few miles?

What else could clearing the EGR passages cause problems with? Catalytic converter? Fuel injection?

[cocobob]

James - did he perform a vacumm test or is he guessing. That's where it can be expensive. Get him to take 10 minutes to do the vacumm test before removing the head. If it is a Valve then the heads will have to come off. Heads and lifters are untouched areas for me so far (knock on wood).

[James806]

I don't know how he would have known the compression was low if he had not run the test. However, he was guessing that it was the valve spring.

I have decided to not let him do the valve job. I can't get rid of the nagging feeling that they did something when they cleaned the EGR valve. I am taking it to another mechanic this week.

If nothing else I will replace the EGR to see if that is it. May be a waste of money. But, I am nearly out of options.

[cocobob]

James before you buy another expensive part such as the EGR go and buy a vacumm gauge for $15. The manual should show you were to hook up the hose and use my previous link for reading what is wrong. You donÈt want to second guess a head-valve problem. This reading will let you know if you have cylinder -ring problems also. If all is Ok then look at components.
Just my humble 2 bits.

Cheers

[James806]

Well,

I took it to another mechanic this weekend. He said it was the valves as well. And the trany is slipping.

There was a link somewhere on this site about how to do a valve job. It had lots of pictures. Does anyone know where that link is?

I may try to do it myself if it is pretty easy.

[Neon806]

Decided to just put a for sale sign on it and hope someone is winning to take it.

Just to be sure it was not the tranny, I had the Trans filter & fluid changed. Fluid was in bad shape but no shavings or anything.

Yesterday it started making a loud noise while the engine is running. Almost like an exhaust manifold noise except it is coming from top of the engine. I had an old Ford truck that had a cracked "heat riser" that made a similar noise. Checked for oil leaks, coolant leaks, etc. Nothing? Engine still runs ok, just noisy.

Any ideas?