well i have a 90 cavalier 5 speed ive been working on. It got hit by a recycling truck and sat for a year i finally started working on it and got it fixed up most of the way ive replaced almost all the sensors on the engine i think the only one i havent would be the idle air control valve anyway it runs alright except when it gets hot it starts backfiring or atleast it sounds like it not all the time though and it seems to do it more uphill ive pretty much had everything apart except the internals of the motor im thinking it may be a broken wire or something but if anyone has had this problem or something similar any help would be appreciated thanks

Kinda sounds like a valve stickin open sometimes. Or Maybe the timing chain is streched a little bit. ..Does it run pretty good when it's not backfiring? I would take off the valve cover and dump some kind of cleaning stuff all over everything in there. you can get all kinda stuff from walmart to do that. Then change the oil. I would also check the torque on the rockers while you have the valve cover off. if you want i can bust out the chiltons and let you know when it's suposed to be.


http://www.j-body.org/members/gnolekaj/cars/1/

it runs alright when its cold i was messing with it the other day and got a rich exaust code i think im gonna get a couple idle air sensors at the junkyard possible valve sticking though didnt think of that it dosent really tap or anything it ran fine before it sat i think it may have been running rich then too i may just replace the timing chain it cant hurt it im not really sure how many miles the motor has anyway

How about a bad ignition module?



JLP
90 Cav<--- "1LE" MPFI car
79 Monte<--- 11.82 @ 112.72

module is newer i didnt replace the coils though

Could poss. be the wire harness between the crank position sensor and the control module. When it cold the conection is good, but once it warms up the conections get loose. The best way to sole it is to replace the female sockets in the harness ends, or the whole pigtail if you can find them, but be carefull as there is a supression wire wraped in this harness.
Also check real carefully for a vacume leak. If yoou have cruise check the small one under the cable.
Hope this helps.


brien
89 Z24

it sounds more like a coil. the same thing happened ton my moms car and I changed the coils and it took care of it

i fixed it!!! it was plug wires they got all corroded put the new ones on runs great thanks everyone for their help