I have just finished up the install of an Elite Engineering Tunnel plate and a new set of Bilstein Shocks, which I thought went smoothly until taking the car out for a very short test drive of about 3 miles. The engine is now missing badly and or shuddering. It began on medium to hard acceleration but now is doing it when traveling a slow smooth pace and at times while idling. I also noticed that the idle seem very low, around 500-600 rpm. I think it was higher before. Does anyone have an idea what I could have done during the install to cause this?

I’m concerned that removing the mid section of the exhaust (H pipe) may have resulted in some problem. I can’t hear any exhaust leaks and I’m sure that the rear 02 sensors were installed in the correct sides (Crossed over). Is it possible that I have damaged the rear 02 sensors during the install? Are you supposed to use a sealant on the threads of the sensors when reinstalling them to keep them from leaking?

From searches I have made today I find comments that the rear 02 sensors would not affect drivability, which I assume means they wouldn’t make it run like it is. Is this correct?

I recall that when removing and reinstalling the 02 sensors I had a hard time keeping them from spinning back when I went to reposition the wrench. This occurred during both removal and re-install. Is it possible that the wires got twisted and somehow damaged? Is there a way to check this?

I just checked for codes on the DIC, finding only 3 history codes for “loss of communication with BCM for the left and right door control module (A0 LDCM 1064 H) (A1 RDCM 1064 H) and the serial data line malfunction with the seat control module (A6 SCM 1255 H). I found there to be no current codes.

I found different results when checking codes using a Predator. There were 12 codes showing, none of which were the ones listed above and none with a “H” after them. Since I really don’t know what I’m doing with the Predator I’m not sure I should be concerned about these 12 codes. The codes showing on the Predator are P0141, P0420, P0430, P0567, P0568, P0742, P1539, P1546, P1571, P1574, P1575 & P1652. Should I be concerned about these and do they have something to do with the missing, shuddering and low idle?

Any help would be appreciated.
Thanks,
Steve

 

You didn'y say if you had to loosen or pull down some headers...I am wondering if you damaged a plug wire moving the headers around.


codes...


P0141 Heated Oxygen Sensor (HO2S) Heater Circuit Bank 1 Sensor 2
P0420 TWC System Low Efficiency Bank 1

P0430 TWC System Low Efficiency Bank 2

P0567 Cruise Resume Circuit

P0568 Cruise Set Circuit

couldn't find P0742,



P1539 A/C Clutch Status Circuit High Voltage

P1546 A/C Clutch Status Circuit Low Voltage

P1571 ASR Desired Torque

P1574 Stop Lamp Control Circuit

P1575 Extended Travel Brake Switch Circuit High Voltage

P1652 Powertrain Induced Chassis Pitch Output Circuit



no idea whcih would cause the problem although the 1st three codes are for the o2 sensors...everything else on the surface seems unrelated to the problems you describe.....sounds to me like something got knocked loose....

oh yeah....www.97vette.com is where I got these codes....there are other links as well Good luck

 

The rear O2 sensors will not cause it to run this way. They exist to allow the PCM to determine if the catalysts are working. Even the primary O2 sensors that control closed loop fuel would probably not make it run/idle that bad.

Sounds like a loose connection, plug wire not connected, etc. What else did you take apart or disconnect?

Reset all the codes via the DIC, and then run the car and check for codes on the DIC again.

 

I love when a vender comes on and helps up with our cars.
thank you ATI
to many venders on here just sell parts and mug us on the price

ATI

 

i always disconnect the rear o2's before removal, pull the 3 clips and unfasten the plastic retainer each side; borrow a set of rear o2's from a friends car

 

cmon man....99% of the time the vendor prices are better than anywhere else....

that being said it is pretty cool the guys who sell the stuff get involved...see it big time with LG and ECS..just 2 examples aside from ATI here in this thread

 

Ill go 90%

 

[QUOTE=pewter99]You didn'y say if you had to loosen or pull down some headers...I am wondering if you damaged a plug wire moving the headers around.


I didn't have to loosen or pull down the exhaust manifolds (headers) at all. Didn't do anything with them except remove the three nuts at the end of the manifolds where they connect to the H pipe section. I have stock manifolds.

The other thing that is confusing is the when checking for codes on the DIC, I only find the three history codes for the door and seat control modules. No other codes are present on the DIC. I found the other codes when I used the Predator to check codes but I'm not sure I am using it correctly (first time trying it). Am I correct in assuming that if the codes showing on the predator they should also be showing up on the DIC? Since they don't I'm not too sure I should believe what the Predator is showing me. Shouldn't it show the same codes on both?

The other thing I forgot to add was that I am not getting a check engine light and the O2 sensor fuse #15 is not blown.

 

Try to identify which cyl. is miss firing. Clear all codes, test drive then diag. codes that set should point you in the right direction. You will need manual, if you don't have the skills to follow trouble tree, take it to a pro.

 

Having never checked the DIC for codes before, I wasn't sure I should reset it. I'll give it a try and see. Shouldn't the same codes showing up on the Predator also be showing on the DIC? None of the codes on the Predator are present on the DIC. Does this mean something?

I'll also check to make sure the plug wires were moved, but I don't remember getting anywhere near them. I double-check this also.

I didn't remove anything else except for what was necessary to install the plate, having removed the front and rear H pipe hangers, the six nuts connecting the H pipe to the manifolds and the 4 bolts connecting the H Pipe to the cat backs.

When I installed the shocks just before the plate, I removed the nuts holding the coolant reservoir and windshield washer reservoir, then lifted them to the side so I could get to the top nut & shaft of the shocks. I remember that there are a couple wires held in place on one of these nuts, looked like it was just to hold them in place. Maybe one was used for grounding? I think I put them back the same way they came off but I will double-check this.

 

never used a Predator...but if they aren't showing on the DIC as Current or History codes I wouldn't worry about them....

it certainly sounds like a loose, cracked or broken wire....thats the problem with plug wires problems aren't always obvious.

Do you have a good old wire laying around?? I always save one or two just for this reason. Replace them one at a time to see if you can track it down.

Good luck man...

 

Thanks for all the responses, keep them coming as any help would be appreciated.

Apparently I should have hunted down the DiabloSport Predator manual before posting. Found it on line and found that the 12 codes I listed were found when checking the section for "Diagnostic Trouble Codes Not Ran". This appears to mean that these codes are not showing up, just were not checked for by the Predator. It appears that there are no current codes showing on the DIC or the Predator.

With the car running so badly, shouldn't I be getting a "Check Engine" light and some current codes?



Shouldn't a bad plug wire cause the check engine light to light and show a code on the DIC? I only drove the car for about 3 miles, would it take longer for the light and code to show?

Thanks for all your help, everyone.

 

a bad plug wire will not show up on the codes... even a marginal coil will not show on the computer

Anytime my car ran like you described... it turned out to be a bad plug or spark plug wire.

VR

 

yep...and this is the cheapest fix...I always start with the cheapest stuff first...

 

Had similar problems once.... check all the grounds eveywhere! BCM comms problems and the door modules sound like grounds. and just to echo the plug wires and/or coil connections. Sometimes things get bumped that have nothing to do with the job at hand.

P15 series of codes look like grounds.

P0420/30 rear O2 sensors or cats. Will NOT cause your engine probs.

The loose ground that gave me a fit was on the rear of the block driver side,and the other one was by the starter. Best luck to you and I hope your all set before you see this

 

I may be getting off track but what do you all think about the possiblility of this being caused by bad fuel and or a a dirty fuel filter? The car hasn't been driven much during the past two months and the filter hasn't ever been changed, only 17K miles. Maybe just a coinsidence that this came up at same time as the tunnel plate install? Would bad fuel or dirty fuel filter cause the same symptoms?

I'll also be sure to check out the grounds mentioned above when I get under the car. I'll also have to check out the plugs and wires. Thanks for all the suggestions.

 

It doesn't seem to be related to the tunnel plate install, or the shocks.
Sounds more like a coincidental engine problem.

Here's a thread link which might offer food for thought...

http://forums.corvetteforum.com/show...956&forum_id=1

 

Front o2's in wrong pipe?? If I remember correctly the front O2's cross. As always, YMMV. Jeff

 

Sounds like you might have the fronts reversed. (VERY EASY TO DO) After checking, pull a couple of plugs from each side and see if one side or the other is running rich. I found out that I had a bad O2 sensor after dropping it.

Good luck

Dick

 

Thanks for the suggestion but it couldn't be the front O2 sensors wiring being crossed since I didn't touch the front ones at all, just the rears. I didn't have to remove the exhaust manifolds or front sensors to do the tunnel plate install.