i have an 86' camaro with the 305 tpi in it. i have an intermittent miss but can only seem to get it to do it when i am giving it throttle typically 25 to 75 percent throttle. The thing that really gets me is it doesnt do it all the time. i drove it to lowes tonight and it acted up under light throttle and medium. on the way home it was perfect! it only sat in the parking lot at lowes for about 8 minutes max! sometimes i can get it to clear up by flooring the gas pedal it takes a second or two of break up then clears up and takes off. its got brand new cap, coil, wires, plugs. ive actually replaced the cap coil and wires a couple of times since having this problem. newer fuel filter, injection cleaner doesnt seem to be helping, and vacumm is dead nuts steady when idleing, unfortunatley cant make it break up while checking vacumm. IDEAS? Please Help! im sooo frustrated!

 

i'm a full time mechanic however im only 22 so the older vehicles, including my own 86 camaro are still sometimes tricky for me as we dont see many vehicles through our shop that still run on the old ignition and fuel systems. so today i asked the advice of our more aged technicians who has had an older gm truck that had a similar issue. he found out he had a weak magnet in the magnetic pickup by disabeling the electronic timing. obvious the pcm no longer has control of the timing but the miss fires went away because the magnet wasnt trying to talk to both the pcm and the module in the distributor. so i tried that and so far it is perfect! im going to put a new pickup in it tomorrow, figure for 20 bucks its worth it even if its not my problem as its never been replaced as far as i know. so i will keep everyone posted as to whether this fixes it permanently or not, but so far so good.

 

Sounds like a TPI issue, try disconnecting it and if it drives better you may have found the problem...had a similar issue 6 months ago and ever since have drivin w/o it connected...hope that helps

 

im sorry disconnect the tpi? you cant take the tuned port injection off the engine and still have it run. im confused? maybe i miss understand.

 

maybe he means TPS switch..that is somewhat adjustible you can turn in to lower Idle. I would maybe lean at the IAC sensor..Idle air..its under the TPS and runs about 35 bucks at autozone..if that doesn't help try running some SEA FOAM threw the engine..cleans everything up.I'm new to these cars so I'm learning also..

 

i've actually replaced the iac, end of last year. this is stored all winter. I was thinking he meant tps, i hooked a jumper wire up today to the sensor terminal and ran it into the passenger compartment hooked to my dvom. so far though i can't get it to act up consistently enough to confirm or deny the tps acting up. since i put the pickup and the ignition module in the distributor it has been a lot better but still has a hick up here and there. i can't imagine the engine is all that dirty considering i just did head gaskets on it three years ago. and my engine oil comes out fairly clean, and it is extremely clean under the valve covers. but i am considering doing a fuel rail cleaning with a pressurized system to directly clean the rail and injectors instead of running stuff through my gas. ill let you know if i can get the tps to act up. i may just replace it again. i put one on when i did the head gaskets but i did buy a cheap aftermarket part so it wouldnt surprise me if the tps is bad.

 

Sorry...TPS

 

2 things came to mind, have you checked for codes? #2 I had an intermittent miss like you are describing, put new plugs, wires, cap, rotor, cleared up for 20 miles started doing it again... Couldn't figure out for days until I popped the hood one night, one of my new wires had come loose and burned near the exhaust manifold... It was quite the light show at night. I didn't think about the wires because I had just replaced them. I forget which code it was but the computer was spitting out a code and it was that I had a short somewhere in the ignition system. I felt like an idiot that I had missed something so simple.

 

i have had similar issues, found out i was routing the plug wires wrong, on the driver side the wires are supposed to go under the engine mount to keep them away from the exhaust. Unfortunatley not whats going on. ive checked multiple times. the pickup has made things a whole lot better. ive also replaced the tps again, i didnt like the voltage scale on the signal wire, but it really wasnt horrible. However i still have a hesistation only once in a great while. did it for the first time yesterday. half hour drive on the eway. once on the way to my second job when accelerating after changeing eways, from 50 back to 70. and then again on the way home accelerating from 65 to 80. only for a few seconds then clears up and drives fine. could a weak spring in the egr valve cause this? i really hate just throwing parts at problems. but i cant figure it out. what about a pcm? has anyone had issues like this that they could explain by plugs wires module pickup or tps? thanks for the assistance so far.

 

ok i went looking today and found a bad ground on the back of the head on the passenger side head. has 3 wires going to it and a ground strap to the body. took care of that and so far its absolutley perfect! Thanks for the Help Everyone.