My Regal misses and jerks between 55 and 65 mph. Also noticeable at 40mph or just cruising at low rpm). Car starts, idles and seems to accelerate fine. No SES light. Plugs (Bosch), wires(Delco), O2 sensor and alternator have less than 10,000miles. New PCV, cleaned MAF sensor with MAF sensor cleaner and sprayed throttle body with appropriate cleaner. Any ideas?

Thanks,
Ray

Why the Bosch spark plugs? What brand of 02 sensor was installed?

It sounds like you are getting what is known as "fishbite" or "chuggle". The effect of the torque convertor clutch locking and unlocking, some engine control problem - fuel injection/02 sensor/TPS, or mild misfire.

When was the transmission last serviced? ATF and screen filter?

I'm afraid transmission service has been 30,000miles. Autozone pushed the Bosch Plats. I can't remember, but I bet the O2 sensor is Bosch, as well. Do you think a trans filter and new fluid would do it?

If it has been 30K miles since tranny was last serviced that doesn't sound bad. I would look into the use of Bosch spark plugs and Bosch 02 sensor as the possible cause before the tranny.

The 3800 Vin "L" and "K" act quirky with non AC Delco spark plugs. For your year model and engine Regal the following are the AC Delco recommended Platinum plugs:

41-601
41-940
Rapidfire 14

Another suitable plug is the Autolite AP (Platinum) and APP (Dual Platinum). These are relatively inexpensive and available at Walmart but work fine. Gap is .060".

Bosch 02 sensors leave alot to be desired versus the OEM AC Delco. The 02 sensor helps control the fuel injection system via the ECM module to keep the air/fuel ratio at the ideal 14:7 to 1. The 02 sensor operation is critical when the engine has warmed up sufficiently and the ECM module switched to closed loop mode operation from open loop mode. Cruising speeds are normally in closed loop mode. The 02 sensor position 1, before CAT is AC Delco part #AFS75.

Thank you. I replaced the plugs with 41-601 and (I may be kidding myself) but there seems to be a significant improvement. Autozone did'nt have/carry the AC Delco O2 sensor. Are any other O2 sensors acceptable?

Thanks again
Ray

Personally, I would stick withe the AC Delco brand. I realize cost is a factor because they are more expensive. The only other brand I would use is Borg-Warner. They have AFS75/105 equivalents. Also, if you do business on EBay OEM AC Delco 02 sensors show up periodically at a reasonable cost.

It looks like they can be had for around $45. I am still not sure what mine is (couldn't see it with a dentist mirror). Since it came from Pep Boys or Autozone it is probably a Bosch.

Thanks for help,
Happy Holidays
Ray

I had a simular problem with our '94 SLS.It turned out to be plugged EGR passages.Also,I have used Bosch sparkplugs in our Cadillac,Ranger,& F-250 with good results.

I have used Bosch sparkplugs in our Cadillac,Ranger,& F-250 with good results.

That is really re-assuring. How about in a GM car with the SI or SII 3800? The bottom line is Bosch spark plugs including the multi-electrode gimmick type are garbage and should not be used in the GM 90 degree 3800 V6 engines.

I have 6 Bosch platinum spark plugs I'll be glad to give away for free.

I have to retract the spark plug comment. I just went down the highway and the miss is still there. It is smooth when the engine is cold.

Ray

Unfortunately, the OBD1 ECM will not give an SES for secondary ignition problems. “Secondary ignition” includes coils, wires & plugs. OBD11 PCM’s (96 up) will give a SES for engine misfires, either random (P0300) or specific cylinder (P0301 to P0306). In addition to the items mentioned in the post above, a weak coil or coils, can cause the symptoms you described.:uhoh:

Thanks. I did get a brief SES that did not come back on when restarted. Since, I have cleaned the EGR valve. My daughters are the primary drivers of this car. They haven't complained over the last couple days. I'll have to find someone who can scan these codes.

Thanks,
Ray

Still at it. I'm trying to test as many things as I can before throwing parts at it. Does anyone have experience with testing the coils? I have a nice Fluke Voltmeter but it is difficult to measure with confidence 0.5 to 0.9 ohms for the primary side. Secondary are all around 5.5K.

Thanks,
Ray

The resistance readings appear good. Coil secondary resistance range is 5000-8000 ohms.

Having the same problem at work with a '96 Regal GS, 3800 SII. Looking to be the TCS. I know it's OBDII as opposed to yours, but it's worth looking into.

Thanks BNAYLOR,you're still there. How critical is the primary side of the coils? It is such a small resistance, I can't tell if is my leads, wires shoved in the slots.....

Ray

For a typical GM DIS System the primary resistance = .50 to .90 ohms @ 70 to 80 degrees F.

Still at it. I'm trying to test as many things as I can before throwing parts at it. Does anyone have experience with testing the coils? I have a nice Fluke Voltmeter but it is difficult to measure with confidence 0.5 to 0.9 ohms for the primary side. Secondary are all around 5.5K.

Thanks,
Ray


On coil testing I always like to check the spark jump cold and then hot.
Most parts places have a spark tester with a adjustable gap tester.
Look for a good hot blue spark and good gap jump.
All coils and wire should be even gap jump.
Good Luck
MT

Having the same problem at work with a '96 Regal GS, 3800 SII. Looking to be the TCS. I know it's OBDII as opposed to yours, but it's worth looking into.

I'm curious what makes you believe your problem is the TCS, assuming traction control system? Or did you mean throttle position sensor - TPS or the torque convertor clutch - TCC?

You'll need to clarify what you are referring to.

My mistake - TCC was what I meant. We flushed the trans and the shudder went away.

Thanks, is the TCS accessable from outside the pan?

Ray