ihave an 1988 gta with 201300 miles on it whne you press on the throttle it stumbles and backfires through the intake unless you go over 3/4 throttle then it drives fine idles fine you can rev then engine no stumble nothing but after a couple of times of doing the 3/4 while drive then going to park at idle you rev it up it does it as well back fires into the intake i though it was a fuel spark problem i have dont a tune up changed fuel filter changed tps sensor and still have the same problem any ideas

 

no one can help me ??

 

Back fire is usually a timing problem, not getting enough advance; or not enough power enrichment when you punch it. My guess without looking at the car would be an ignition module failing, or fuel pump or injectors going bad. You didn't mention how long you have had the car. Did it used to run fine for you and these symptoms just started, or did you just get the car and it has not run right since you got it? Have you done any modifications to the engine?

 

Do a compression test on all the cylinders. You may have a cracked intake valve. There are other possibilities as well, but you have to start somewhere.

 

I agree, sounds like a timing problem. With that many miles, your timing chain could have stretched and skipped a tooth???

 

ive had the car for 2 years now was going to be a street/strip car but bad luck its now my dd. no mods to engine other then a k&n airfilter ill check the timing to see what its at then car just statred to do this out of no where was driving came to a stop then left the light and it started ill check compression and the timing thanxs for the advice ill let you know how it turns out

 

ok check timing it shows 8 degrees btdc but when the engines go up it jumps to over 12 + degrees btdc i dont get it it isnt advancing

 

back fire in the intake means igntion of the fuel is coming before intake valve is closed back fire from the muffler would means igntion of the fuel before the exhaust valve is closed check plugs,valve lash,spings and push rods have u done any work on motor lately?

 

nope other that tune up no engine work done

 

its defently an igntion problem,i can help u more but rite now i got go but ill be back later and post more advice sorry

 

Does the SES light come on? Have you checked for any stored codes?

When you checked the timing, was the EST bypass disconnected? If not, you're severly retarded (timing, not you )

 

est was disconnected timing shows 8 degrees but when the engine rps go up it jump up to aobut 12 plus degrees btdc it doesnt adv with the est on i was checking with light and no advance and no ces light
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i did s low rpm range test and it came up from 1200 to 3000 in that range it stumbles and feels like the engine is holding back but after the 3k it goes up fine from there

 

Re: the advance...when it advances to 12 BTDC, is that with the EST bypass connector UNplugged?

 

does the car idle?at what rpm does it backfire? pull the plugs one at atime and check for color change

 

Are you confusing the ESC with the STC - Set Timing Connector?
To check, or set the initial timing on my TPI '88 I disconnect the STC disabling ECM control of the timing which isn't the same as ESC module - Electronic Spark Control (spark retard.)