Unknown Backfiring

smsubarus · Post by **smsubarus** » Wed Jun 23, 2010 10:46 pm

I have a 1985 turbo RX leone that will not stop backfiring on acceleration and deceleration. It will also not rev past 4000 revs, but has no trouble idling. It is not blowing any smoke. Does anyone have any ideas as to what may be causing the problem?
Thanks,
Marcus

Gannon · Post by **Gannon** » Wed Jun 23, 2010 11:02 pm

Pull off the timing belts and check your cam timing. You may have skipped a tooth

Wagonman · Post by **Wagonman** » Wed Jun 23, 2010 11:07 pm

Also check and clean or replace your spark plugs..an inefficient burn can cause backfiring.

steptoe · Post by **steptoe** » Wed Jun 23, 2010 11:13 pm

coil, HT leads, did it develop slowly or suddenly or did you buy it like this, after lending it to friend, the missus, any mods, what have you checked. Think Gannon means pull off timing belt covers to check the belt timing marks which is different to ign timing

twilightprotege · Post by **twilightprotege** » Thu Jun 24, 2010 12:35 pm

going off my own experience - ignition timing is my guess

steptoe · Post by **steptoe** » Thu Jun 24, 2010 1:35 pm

backfire through exhaust or popping through intake side ?

smsubarus · Post by **smsubarus** » Thu Jun 24, 2010 4:44 pm

Thanks for the ideas. I have just found papers from the last owner saying that the motor was imported with 80,000kms on it and has now done roughly 100,000kms, going by the previous owners records. The backfiring is coming through the exhaust and I bought it like this.

AlpineRaven · Post by **AlpineRaven** » Thu Jun 24, 2010 9:00 pm

My money is on Timing or Distributor at fault... Keep us updated.
Cheers
AP

steptoe · Post by **steptoe** » Fri Jun 25, 2010 12:20 am

Time to swap bits from your other 85 RX ya greedy thing.

Dizzy cap from memory is GH617, rotor button from same memory GH609 H is for Hitachii dizzy - about 30.00 for the two. Spend on the easy basics and when you do plugs a comp test also helps determine if belt has skipped a tooth, I think factory manuals recommend new spark plugs every 10 or 20, 000km for the EA82T

Just pull two small camwheel covers and timing bung plug, find the belt timing marks on flywheel look like this lll found 90 degres turn away from ignition timing marks, one belt timing marks should line up, full 360 turn back to these marks in fwd turn should then line these marks up with other side timing belt marks. Have more tips on setting timing to near 20 DBTDC with pics

Jonno, have 86 GLTA EA82T 3 plug computer, vac adv dizzy,

tony · Post by **tony** » Fri Jun 25, 2010 2:19 am

hole in muffler, faulty spark plug or plug lead, running lean.

smsubarus · Post by **smsubarus** » Fri Jun 25, 2010 9:54 pm

Thanks for all the help. I have changed all of the plugs, filters, leads and also put in some fresh fuel (as it had been sitting around for a while). It is revving better, stopped backfiring on acceleration but still backfires on deceleration. It is revving better (still not 100%) but the power isnt reaching the wheels, so as the revs go up, the power doesnt increase like it should. Its going like a slug. According to the the last owners records it looks like it has been professionally converted to a rear wheel drive. Thanks again!

steptoe · Post by **steptoe** » Sat Jun 26, 2010 10:33 am

Can you get a timing light on things? 20 DBTDC. Slippng clutch? Dizzy cap and rotor next?
Good stuff, you are getting there !! Hmm RWD ?

smsubarus · Post by **smsubarus** » Sun Jun 27, 2010 8:26 pm

All fixed and running well. Distributer at fault!
Thanks for all the help again!
As car is a rear wheel drive and only has a standard open diff, just would like to know how strong rear axles are? because I am looking at welding the diff up. Car will be getting used for racing in autocross.

steptoe · Post by **steptoe** » Sun Jun 27, 2010 9:49 pm

gunked up mech adv gizmo ? too much play ? ignition module?

good to see fixed