Backfiring

[beandip]

I know this is an old thread. But it the issue is similar to mine. I have 75' 280z, it hesistates on acceleration until about 2-3k and it will accelerate normal again. I'm getting backfire in the intake. It all started happening after I installed an ebay cai, and msa headers. The header bung is closed, but the EGR is still open, not sure if this will cause these kind of symptoms.

Things changed: fuel lines,vacuum lines, regrounded wires, intake couplers, spark plugs and wire.

The car has ran perfectly fine before the installs.

Any help is appreciated.

One thing this could be from is a vacuum advance not working properly. If you have a timing light , use it and run the RPM up a little. Then disconnect the vacuum line to the vacuum diaphragm and see if it changes the advance. Another way is to remove the dist cap and suck on the rubber vacuum hose while looking down into the dist . you should see the breaker plate move about 3/16 or so, put your tongue over the hose and hold the vacuum. If there is a leak you will know it . if so replace the diaphram. I could be one of the sensors on your injection , I frankly don't know injection. But I do know ignition fairly well. Gary I may not use the correct terminology all the time but my cars run great. I have been into cars for over 50 years and have never heard of ''afterfire''. Gary

[Obie87]

I am also having this problem. The car is running really strong when its cold, but one the engine warms up I get a highly noticeable power loss, especially at low RPMs. Occasionally during acceleration under any load there may be a backfire.

I am a Z-idiot (but learning about cars as I go along) so please use small words and don't expect me to know more than the average joe about working on cars.

Thanks all,

Rob