My 1998 Lumina is once again Hesitating and acting up. In February we replaced the coils and Ignition Module. A few months earlier we replaced the plugs and wires. It was running great .... Now its not!!

HELP! Does anyone know what is on the other side of the ignition module?

When I drive down the road the car sounds like a bucking bull its hesitating and bucking. at all speeds.

I have seen on this board that it may be the cam sensor. Could it be? Does anyone have any insight? The check engine light is not on. (it was on until I replaced the module)

Also would like any information on flushing the radiator. The pivot valve is not visable to drain it... Would like to do this also but can not find how to drain it.

Thanks in advance!

The petcock in on the l/s of the lower rad tank, go to get under to access. Although your descriptin is good it is still vague, this problem can have many causes, have it scanned for pending codes and pending misfire codes, recheck all you plug wire connections also.

Well let me try to elaborate what is happening with my car...

I get in Start it up prrs great - runs smooth --- I head down the highway and the car begins to hesitate (slip like) I can race the engine past it or slow the engine past this fit the car seems to be having but then it happens again. imagine if you will a mechanical bull, you hop on and put the quarter in you have a few seconds of smooth then its back and forth longer sometimes shorter strokes of power surges -- I had this problem last year and Chevrolet diagnosed it as Spark Plugs,,, So we replaced those along with the wires, it cured the problem for a month then it started again, not so obvious but there So we came to this board and read and read and someone else was describing the same thing its like you have sliky pants on and you sit back in the seat and next thing you know your scootching back.... and they replaced the coils and ignition manifold so I said what the heck and did it too $250 and 4.5 months later its back!!!!
I am a single mom and will invest what is necessary to do, but today on my way home it was horrible (fine on way to work) I was in granny lane cruising with traffic @ 40 mph then it Sliped - bucked - what have you it just kept up and I only drive 8 miles a day!!

Thanks for the Peacock position!! Thanks for all advise!!! It is so appricated!!!

Again, I understand what you are describing, have owned the same car, this still could be an intermittent ign misfire, or a trans lock up up convertor locking and unlocking, that is why the suggestion of the full scan especially as it happens, if I were to drive this I could be more definitive in my help here. An experienced tech should, by seat of the pants feel and scan results, be a able to pin this down.

If you have someone perform a full scan, ask to get a report of injector timings. I've seen Multec injectors get "intermittent" (for lack of a better term) without actually failing. Any fuel pressure fluctuation can have the same results, and is not diagnosed or monitored by the PCM.

ts like you have sliky pants on and you sit back in the seat and next thing you know your scootching back....

I cannot honestly say I've ever considered silky trousers as a diagnostic tool - I'm sure it would be popular...

( : Thank you for the info. & The Smile! Well I took it up to Auto Zone, They Scanned it with 2 computer things and no codes - misfires - nothing the guy seemed to think it maybe the fuel injectors he said try some cleaner he suggested Lucas so I bought and put in tank then filled up.. now I am waiting.. only drove 4 miles since hopefully some change soon!

While I have ya all here, I thought of replacing the spark plugs and wires again because I feel like witts end here and when I called around my mouth is still on the floor for prices... Pepboys wanted $111 for plugs $40 for wire set then 75.60 in Labor... Good year - Firestone - where a little more is this for real? We had trouble with the 3 plugs in the back but were able to do it our selfs a few months ago for $50 wires & double platn plugs... just curious..

Well thanks, L

Search your data and/or receipts. What plugs did you install a few months ago? What wires? I caught the "double platinum" part, and so long as they are not "designer" pligs (like SplitFire or Bosch) they should be adequate. If they are single side electrode, double platinum (platinum for both the center and side electrodes) and were gapped properly, they should be fine.

My guess is that Ought-Tow-Zone recommended the Lucas fuel system cleaner because that's what they sell. I've had the best luck with Chevron Techron cleaner, but even that is only a preventive maintenance treatment. If you have an injector(s) already plugged, streaming badly/poor spray pattern, or leaking, it may not solve any of those problems. Not much would, short of removing the injectors for ultrasonic cleaning, reverse flushing, new inlet screens, and flow-matching.

The good news from the scan (if performed properly) is that there are no misfire indications, no rich- or lean-errors, no MAF or other significant sensor errors, and no apparent hard codes (defined problems). If the scanner also looked at pending codes, there may have been some more data, but we don't know that. The PCM monitors primary ignition/timing and emission performance rather closely. If there was a problem with teh coil switching (ignition control module) or coil primaries, the PCM would tend to detect that. What it doesn't care about as much is the raw fuel delivery, engine menchanical condition, and secondary ignition system (the high voltage part). There is no means for the PCM to monitor fuel pressure, and short of injector timings and eventual emissions data, no means of monitoring fuel delivery and it's effect on combustion. A streaming or leaking injector may never be detected other than by the performance and driveability. The fact that it idles smoothly and starts easily would tend to negate any low-flow rate injection problems.

The mechanical condition could affect operation, but typically has a more noticable affect at or near idle. Unless it idles rough in gear, chances are that compression is approximately equal on all cylinders. You can warm the engine to normal temperature, hold the brake, engage DRIVE, and slightly raise the engine RPM with the accelerator. If there is noticable shaking, misfire, roughness, or stumbling, there may be a mechanical problem such as valve leakage, wiped cam lobes, poor ring sealing, and any number of other possibilities. If it runs smoothly and quietly, chances of a significant mechanical problem are low.

That leaves the secondary ignition (again). Make sure the spark plug wires are routed properly, not damaged, burned, or pinched anywhere, and are properly connected at each end. Inspect the coil pak and base for contamination, proper connections (including grounding), and signs of moisture or carbon streaking/arcing.

The other thing that concerns me is the mode in which the problems are ocurring. Part throttle, low-load cruise operation is precisely when the EGR and EVAP canister purge functions are supposed to occur. If the EGR valve is not operating at all or at the wrong time, the PCM will detect that. If the EGR flow is incorrect, however, the PCM will frequently not detect that until it has affected emission to the point of a failure. A similar situation can occur with the EVAP system.

The last concern is fuel. If you are refueling at the same place regularly, find a different source for fuel for about 500 miles of driving. Don't bother buying a higher grade or octane than you need. Clean, fresh 87 octane should be all that's necessary. 10% ethanol should be fine, and may even help in your situation. It's possible that your fuel supplier has a problem with keepig clean, relatively dry fuel, so changing may yield some positive results. And it doesn't cost anything more.

I agree with Blue, that if they installed Bosch Platinum +2 or +4's, there is a good chance that's where your miss is coming from. Those gimmicky plugs are absolute junk. Stick with AC-Delco or Autolite Double Platinum's.

Wow,,, THANK YOU, I am printing this going to go re-read it and will be back to update ya'll WOW Thank you soooooooooo much!!!

hiya all. i'm kinda bumping this to avoid a new post- my cars doing the same thing and was tested and not sure the exact number of the code but i did see the code on the scanner and crosschecked it with the code book and mechanic friends. it was the EGR valve code. I know my problem may not actually be the EGR valve but I would like to plug it to check before i buy a new one and replace it. the trouble is WHERE might i find the EGR valve? lol I have seen pictures and i know where it was on my old truck i used to have but I don't seem to remember what it looked like nor seem to seem to see anything looking like the pics i have found online of it. And have no Haynes or Chilton book for this car atm. :( And the worst part of it is my mechanic friend is in jail on child support crap so i can't ask him. Thanks in advance.

(short version=where's my EGR valve?)

1993 chevy Lumina 3.1 vin "T"

Look here:

http://72.19.213.157/files/3.1V6EGRValveView.jpg

tyty sry it took me so long to reply back but thank you very much - was helpful :)