Hey everyone. I need some help regarding some questions with my car. The car is a 1997 Camaro Z28 with 70,000 miles. I'm a newbie to this sight but everyone recommended it. The guys in my car club said there are some good folks on here so I'm hoping they're right. I have not had any problems with the car and the car was running great. Now, at 70,000 miles I decided to do a plug change because I'm not sure when the last time was that they were done since I'm not the original owner of the car. I've done all the mods but the plugs looked original OEM. I bought a set of Bosche 2 Platinum plugs and replaced all the plugs. I took it out for a test drive and had a slight stumble loss of power at low RPM from starting rest to about 65 or 70 MPH. After that speed, it seems to "catch" and run and feel like it's running normal without a hitch. MINOR MINOR rough idle as well. Then it eventually threw some codes. I hooked my scanner up to it and scanned the ECS. I got a P0151, a P0300, and a P0305. For those of you experienced in the OBDII you know that's an O2, a random misfire, and a cylinder 5 misfire. I dismissed the O2 and cleared it because i used a lot of PB blaster on the exhaust and it was bank 2 sensor 2 which is post cat so I didn't see it causing much of problem. I came back home and pulled the number 5 plug, inspected it and RE checked all the plug wires as I checked them all when I did the plug change. I then read on several of these forums, where many people advised against using Bosche and the platinum plugs so then I went to the Chevy dealer and bought some direct AC Delco replacement plugs matching part number and everything from what came out of the engine. I put the Delco plugs in and went out for another test drive. It didn't stumble or misfire or lose power AS BAD but it did the exact same thing. I'm not sure what if anything a simple spark plug change could screw up to cause a misfire when everything was fine before. My only idea is that I might have broken a filament inside a wire moving the wires out of the way to pull the plugs out when I did the plug change. The wires LOOK great but as far as their resistance qualities and internal shape I'm not sure. They APPEAR to be the original OEM wires that came on the car new so I'm not sure they have ever been changed out. If not, then they are probably very brittle from the heat and I don't think it would take much movement to mess them up. I have already ordered a new set of AC Delco wires from the dealer and they will be in on Monday so I will put them on then. My questions are as follows: has anyone had similar issues after something as simple as a spark plug change? If you have or even if you haven't, does anyone have any advice about what could have caused it or what i should do? My oil dip stick has broken the little plastic piece up by the handle so I removed it to keep the piece from traveling down into the oil sump. I don't think this could happen but a friend of mine suggested maybe the problem is from doing the test driving without the oil dipstick in place because the system is not sealed anymore. Does anyone else think this is possible? I dismissed it but I guess anything is possible. And the other questions are more or less brand / type / preference questions. Does anyone have any recommendations or preferences about which spark plugs are the best for this year LT1? And does anyone have any recommendations or preferences about which spark plug wires are the best for this year LT1? Also, I heard so many horror stories bout the spark plug changing on an LT1 and I have to say the first time, I did agree it was a doosy, but now I've got it down to where i can change all 8 in 45 minutes. Does anyone have any suggestions or ideas or links to writeups on how to do an LT1 spark plug wire change? Help on this would be greatly appreciated! And lastly and again I'm repeating, does anyone have any idea what causes this or has it happened to you. Lots of LS1 experiences on the net, not a whole lot of LT1 experience. Please write back.

 

I would bet that the new plug wires will clear it right up.

 

P0151 is for Bank 2, Sensor 1 (pre-cat) stationary lean condition. I wouldn't dismiss it.

 

I am having the exact same issue with my 94' caprice LT1. New plugs, wires, injectors, fuel pump, filter and regulator. Still is idleing like crap and has a hard time with anything throttle other than a very slight acceleration.

If I give it any kind of pedal it will backfire and stumble but then catch up and run like a scalded dog as my dad use to say.

I have tested all sensors (MAF, MAP, IAC, TPS) and they all check out OK. I think I have narrowed it down to Cylinder # 8 as when I disengage the injector connector the RPM's do not change and there is no noticble change in the engine performance.

I checked the inj plug with a noid light and it is getting a signal and I also changed out the spark plug with another new one as well as double checked the resistance of the plug wire. everything seems to be OK.

Tomorrow I will plug my spark plug tester in to make sure it is getting fire and I will also swap my # 6 and 8 injectors to rule out a faulty injector.

If I do that and all checks out I will be at a loss as to whats wrong. If my ICM was going out wouldn't it affect all cylinders? same with the coil?

 

There was a guy on a now defunct website (www.ws6zxr.com) that chased down a rough idle and stumble/hesitation off idle for a couple of years. I'll bet he changed almost every sensor in the engine as well as the opti. The problem didn't clear until he changed the O2 sensors. It never threw any codes and none of us..that I can remember..could figure it out nor expected it to be the O2 sensors. Bottom line, don't ignore any info or hints that you get...that PO151 code might be the answer.

Also, the stock AC Delco plugs can cause problems with idle when the little platinum plugs fall off. I know my idle cleared up when I changed to the NGK TR5IX plugs when my car was stock. Your plugs are new so I doubt the pucks fell off just yet. Just a little reminder for the next time you have to change plugs...

Another thing that has an impact on idle quality, beleive it or not, is crankcase venting. On my wife's LT1, fixing the oil leak issue at the back of the intake manifold made it idle smoother. Maybe it was due to sealing the crankcase, maybe it was the new manifold gaskets...I don't know. Anyway, the dipstick being open might have an impact on idle quality. Why not, temporarily, put a vacuum cap over the tube and see if there is an improvement.

Good luck...chasing down problems like this can be a pain...