Hey everybody



I have an 1986 mazda rx7, the old owner told me he put in an 1991 engine in. When I bought the car it was really backfiring and missing like ****. Then I parked it for about 1year. Today I went to try to start it up and it did without much trouble but it won't idle on its own, and backfires less than before but it still does. The thing is when I rev it up past 4000rmp the back firing slows don't tremendously, but once I let of the gas and hold it at about 2000rmp its starts backfirng.



I was wondering what the problem could be. I checked the compression by removing the plugs, egi comp fuse and disconnecting the coils, then I got my bro to turn the enigine over and I listened for the compresion and it sounds really good. I have a doubt on the coils but i'd like some advice from other owners as maybe they have experienced this.

My old 88 GXL did that for about 2 weeks, don't know if its the same problem I had, but with mine it would stutter real bad while its doing that it stoped for a few weeks then came back and got to the point where it backfired at high RPMs too. 2 days later I was stranded on the side of the road with smoke rolling into the car from the torn shift boot.



I never did find out what the problem was, but I was told that from the sound of it it was a easy fix. (didn't believe the stealership though)

Either is too retarded or the Spark plug wires are crossed....



Check the timing

TPS is always a good bet too.

Hmm... check if it's running rich. Check the oil level, see if it's old and nasty, clean your spark plugs or get new ones, make sure all the Trailing and Leading plugs are in correctly. It sounds to me like you're just running really rich.

I checked to make sure the wires are in the right spot, also the plugs are new



Now how would I check the timing, and where is the TPS located. And just for reasurrance, the blue band plugs go on top for trailing, right?. And how would I adjust whether it is running rich and how would I check

could be stale gas as well

Here is a timing write up, just need a light: set timing



The TPS adjustment is in the faq section too. I don't remember which plugs have the blue bands. Take them out and read the #'s. The leading should be BUR7EQ and the trailing BUR9EQ.

dont just judge them by color... trace the wires back to the distributers. one set says L and the other T.



a good idea that i thikn would fix this problem is to give your car a full self tune up. change spark plug wires, plugs (but you already changed them), fuel filter, oil filter, flush your oil, flush your coolant, check tranny fluid level.



all of those things shouldn't take you too long. and i KNOW that it will make your car 1000000000 times happier

I changed the coils this morning and car ran beautifully ( no backfire or miss ), so I decided to take to for a drive, it stalled the minute I put it in gear, but started up right away, but now it backfires more than what I started with, but it will stay idle. Then when I was driving it I had to have one foot on the gas and one on the brake to keep it idle, then it would take time picking up speed.



I think that it has something to do with the timing but my dad says one rotor isn't working. But then why would it run beautifully, and then just start backfiring.

I have read here that people with a bad TPS have also experience backfires, missing, and no idling but they couldn't rev up really high. In my car it does all this except that my car can run up till the read line without much difficulty.