I have a 87 iroc pretty obvious but my car is missfiring and doesn't like it when I first start her up. The car will put down the street for almost an entire block sometimes before it starts to run right. It's usually only bad when I haven't ran the car in a while. But no matter what, everytime I'm in first initially it doesn't respond right it pops and the car jerks forward then slows down. It's really quite annoying. Once I get into second the car works fine. It's a 5.0 TPI and the car isn't throwing any codes. I recently descreened the MAF and put in new spark plugs some bosh 4+ platinum's. Anyone have any idea? I really don't want to take it into a mechanic and pay $50 so they can tell me to replace a part. Thanks.

 

Start off by double checking the ignition. Make sure your wires are positioned correctly(firing order is correct) inspect the wires for damage, check the timing with a timing light, check to make sure there is no moisture in the cap etc. Start here then move on.

 

If you have a few bucks try putting in a new O2 sensor. They seem to need replacing every 2 years or so. Just a thought.

 

Thanks for writing, how do I check the timing? You said with a timing gauge but how do I get that and how much are they? Also how do I check the cap? How many O2 sensors do the 5.0 TPI's have?

 

I dont think its really a timing problem cause you say it doesnt happen when its warm. Dont waste your money on a gun unless you plan on tinkering with your car a lot. Take it to a shop. It takes only a minute or two. I only listed this stuff to check since you said you changed the plugs and you might as well check the system over. Its easy and quick. I really think its an O2 sensor cause my car did that too but you never know. There is only one sensor and it should be on the drivers side downpipe.

 

Thanks, I bought the O2 sensor is there anything special I should know about installing it. Should I take it somewhere and have it installed? Do I really need a special wrench?

 

Try this first. Take a spray bottle and set it to fine mist. One night in the garage after the car has sat for a while to reproduce the symptoms, turn off all the lights and start the engine. Spray the mist around the plug wires and see if you get it to light up. If so, you have bad wires. Don't forget the boots and the plugs too. Those can crack.

On the cap, you have to take it off and look on the inside. If the terminals look good (compare with one at the parts store) then you are fine there. If not (looks like crud buildup on the terminals) then replace the cap. You can get a special socket for the O2 sensor or if you can get a wrench on it, that would be fine.

What sensor did you get? Hopefully it is a Bosch one. I have had better luck with them. If it doesn't have anti-sieze on the threads, it would be good to dab some on the threads.

 

I'm going to be replacing my spark plug wires next I was going to buy them at AutoZone but they didn't have them in stock so I have to order them. I did buy a bosch O2 sensor and it does already have the antisieze stuff on it. However I don't see how I can get anything but a socket wrench onto my O2 sensor. I was just taking a look at it and there is no way to get at it from the bottom just the top. It looks like if I take 2 spark plug wires off and then use a socket extension with a special socket wrench it wouldn't be too hard to get off.

 

I changed the O2 sensor and my spark plug wires. The car only miss fires at really low rpm's pretty much anything before 1500. Usually just in first gear because that's the only one I'm usually below 1500 rpm's in. But sometimes I'll be in forth and pop it into 5th and the rpm's drop to just below 1500 and the car will make the popping sound and not accelerate. Any ideas. I'm going to take a look at my distriputar and my rotor but I thik that was checked a little while ago. Any ideas?