90Cutlass3.1 Posted September 30, 2008 Report Posted September 30, 2008 I have a 3.1 MPFI that occasionally surges at highway speeds. Kinda acts like the a/c pump is kicking in and out real fast, but it is happening with the a/c off. Doesn`t happen all the time just once in a while, seems to be the worst when the engine is warming up to temp however it will happen once in a while at normal operating temp. Doesn`t matter if I have the cruise control engaged or just driving by foot. It will rev up a couple hundred rpm`s then drop back down about the same amount then go back to normal. I just put in new bosch platinum plus plugs and new plug wires. Replaced the coil pack awhile back as it went out. I need to do a trans filter and flush. Would this have anything to do with it? Car has been setting for a few years before I got it back running a few weeks ago but it was doing this before then also. Any ideas? Quote
ns87 Posted September 30, 2008 Report Posted September 30, 2008 Our engines don't do well with platinum plugs. Just get some regular a/c delcos. When the car does the surge, try lightly tapping the brake pedal (while holding acceleration constant). I'm willing to bet the engine RPM jumps and will stay high. That is your TCC lockup kicking in and out. It wouldn't surprise me if yours doesn't work right, because mine hasn't worked at all for the last 4 years. Quote
Crazy K Posted September 30, 2008 Report Posted September 30, 2008 new bosch platinum = bad for car. Quote
Night Fury Posted September 30, 2008 Report Posted September 30, 2008 new bosch platinum = bad for car. qft Quote
Brian P Posted September 30, 2008 Report Posted September 30, 2008 Back on topic Thread purged. Step 1: change out spark plugs for anything but Bosch platinums (especially if they're the +2 or +4's) It *might* be trans related, or converter lock-up related. It's hard to tell without seeing exactly what it does. Is the Trans fluid level okay? Quote
90Cutlass3.1 Posted October 1, 2008 Author Report Posted October 1, 2008 I will change out the platinum plugs but it was doing this before I put them in. Actually the old plugs didn`t look that bad, engine seems to have been burning pretty clean by the condition of the old plugs. I does run smoother with the new plugs so i`m sure that it needed some, don`t know if they were the originals or not since I bought the car used, but they were AC Delco`s. Trans level is full and fine What is TCC? Thanks for the help. Quote
1990lumina Posted October 1, 2008 Report Posted October 1, 2008 Torque converter clutch. Does it surge at a constant speed, or lightly accelrating/deaccelerating? Quote
90Cutlass3.1 Posted October 1, 2008 Author Report Posted October 1, 2008 Surges at a constant speed. Speedometer stays the same. Quote
Addicted To Boost Posted October 1, 2008 Report Posted October 1, 2008 This could also be a misfire.. what condition are the sparkplug wires in? Coils and ICM? Quote
90Cutlass3.1 Posted October 1, 2008 Author Report Posted October 1, 2008 Plugs wires brand new just replaced. Coil pack was replaced about 400 miles ago (checked out fine ) but it was from a salvage yard and ICM dunno, any way to check it? Quote
oldscsc Posted October 1, 2008 Report Posted October 1, 2008 Plugs wires brand new just replaced. Coil pack was replaced about 400 miles ago (checked out fine ) but it was from a salvage yard and ICM dunno, any way to check it? Coils are kinda tricky, they can test good and be bad Quote
Addicted To Boost Posted October 1, 2008 Report Posted October 1, 2008 You can remove the ICM and have an auto parts store test it for you. Make sure the other 2 coil packs are good. I think auto parts stores will test coils as well. Quote
90Cutlass3.1 Posted October 1, 2008 Author Report Posted October 1, 2008 You can remove the ICM and have an auto parts store test it for you. Make sure the other 2 coil packs are good. I think auto parts stores will test coils as well. Will do. Thanks the the help all, I`ll let ya know. Quote
oldscsc Posted October 1, 2008 Report Posted October 1, 2008 Mine with lip tails Normal tails with custom spoiler Convertible with trunk rack Quote
ManicMechanic Posted October 1, 2008 Report Posted October 1, 2008 Just wondering why you're posting these pics in a ICM thread... Quote
oldscsc Posted October 1, 2008 Report Posted October 1, 2008 Just wondering why you're posting these pics in a ICM thread... I was talking with him in the other thread...I got mixed up He knows though Quote
90Cutlass3.1 Posted October 1, 2008 Author Report Posted October 1, 2008 gotcha... guess i`m not the only one that does that. Quote
89SupremeCutty Posted October 1, 2008 Report Posted October 1, 2008 Just wondering why you're posting these pics in a ICM thread... x2 lol. talk about a thread being derailed. my 98 lumi does the same thing every once in a while. Quote
ns87 Posted October 1, 2008 Report Posted October 1, 2008 Just remember when you go to the autoparts store, they will have no idea they can test the ICM. D-1929(maybe D-1926) I think is the connector they use to hook it up at advance auto parts. Be insistent and don't be in a hurry. It will take them a long time to figure it out I'm guessing Quote
90Cutlass3.1 Posted October 1, 2008 Author Report Posted October 1, 2008 Tried tapping the brake pedal today on the way to work and didn`t make any difference, so don`t think it`s the TCC. Leading me to believe it is a misfire of some kind. Noticed a slightly rough idle once I got to work also and could hear it misfire occasionally while listening to the tail pipe. I`ll get the ICM tested but may take me a day or two before I can get to it. Quote
ManicMechanic Posted October 1, 2008 Report Posted October 1, 2008 Have them test the ICM at least 5 times, often they will show as being good until they are warm then they will come up as bad. Quote
90Cutlass3.1 Posted October 2, 2008 Author Report Posted October 2, 2008 Pulled the ICM off this evening and will have it tested tomorrow. Once I had the coils and ICM out off the way I noticed that one of the connectors going to the ICM had been previously spliced with BARE wire showing!!! The likely suspect Still going to have the coils and ICM tested tho, not going to all that trouble without at least having them checked. Quote
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