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Idle low and back fire


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12 replies to this topic

#1 Prospeeder

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Posted 22 November 2006 - 12:16 AM

Mmmkay well this has me stumped. I replaced the Coolent temp sensor plug, and cleaned the terminals, thinking it would fix this problem, but it didnt,it just made my idle quality better and ALOT more low end power. Problem

When started, idles fine, no backfire, drive it, turn it off, do what ever, restart it, the idles REALLY low somtimes it nearly dies, and when u rev it its slow and when u hit prolly 900 it backfires through the intake and the turbo light flashes. You drive down the road abit and the problem disapears and only comes back when u turn in off and restart it. Whats up??

#2 Frank B

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Posted 22 November 2006 - 08:24 AM

Have you checked for fault codes yet?
it may be ignition or timing related.

#3 Durania

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Posted 22 November 2006 - 01:03 PM

Could it be running rich? I heard making a turbo'd car run real rich can make it backfire pretty hardcore.

#4 Prospeeder

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Posted 23 November 2006 - 03:33 AM

Hmm no i havent checked for codes, no check engine light at all. I dunno if its running rich, because its intermittent, it will only do it when started warm, or warmish, if its cold or is drivin around a little it shows absouluty no sign of this issue and ides smooth and perfect and revs with no backfire.

#5 scrap487

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Posted 23 November 2006 - 03:47 AM

ok may be a long shot, I dont know crap about ea82s or turbos... but do you let the car cool down before you shut it off? ie let it idle for a minute or two at least before you shut it off after driving it? next time you drive it try letting it idle for a while before shutting it off and see if it still does it as bad if at all?

#6 Prospeeder

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Posted 23 November 2006 - 01:45 PM

yea i do let it cool off, it doesnt have an effect on it tho

#7 NorthWet

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Posted 23 November 2006 - 04:49 PM

Backfiring through the intake almost certainly is not a rich mixture situation... that would tend to cause backfiring (afterburning) in the exhuast.

I would agree with this being ignition related. If it were happening all of the time I would seriously suspect valve problems: Either a burnt valve or one that was sticking in the guide and not seating properly.

Is the ignition timing adjusted properly? If so, to what value? Is this on your 86 EA82T? Flapper-style MAF and vaccum advance (and retard??) on the distributor? The advance mechanisms might be sticking/failed. The vac advance may be moderated by a thermo-vacuum valve which may have issues.

Also, don't overlook sparkplug and wires. Wires can fail or become marginal after very short distance/time. The IAC might be another culprit, at least as far as low idle speed. (And I assume that you know the turbo light is just from the backfire overpressure.)

#8 Prospeeder

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Posted 23 November 2006 - 07:22 PM

hmm the idle picks up if i push REALLY hard on the plug of the CTS, i cant seem to get the plug on there well enough. Also when this is happening, the car is gutless and jerks through its power band, and then it just gets over it, idles great, no back fire, pulls pretty hard.

Yes this is my 86 EA82 w/ Flapper style MAF and vacuum advance. Plugs are brand new NGK's i put in, the wires...i dunno.

#9 NorthWet

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Posted 23 November 2006 - 09:01 PM

hmm the idle picks up if i push REALLY hard on the plug of the CTS, i cant seem to get the plug on there well enough...

Sounds like where to concentrate your attention. I took the advice of grossgary and soldered wires at the CTS, leading back to a more accessible and serviceable connector.

#10 Prospeeder

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Posted 24 November 2006 - 02:30 AM

hmm that may be an idea then, think i can get to it all in the car, or will i have to remove the sensor?

#11 NorthWet

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Posted 24 November 2006 - 12:25 PM

I feel it is far easier to pull it out to do it (not even sure if it is possible in place). I cut down the plastic connector on th CTS to get better access to the CTS pins. Be aware that once wire (and connector) are added you need a deep socket or cutout socket (like O2 sensor socket) to reinstall the CTS.

#12 Prospeeder

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Posted 24 November 2006 - 12:56 PM

ah no possible way a wrench can get in there i take it? i have a deep 17mm socket, im not into going to shucks and buying an 8-10$ socket, lol, for one time use

#13 daeron

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Posted 24 November 2006 - 11:05 PM

one could always take the cheapest socket you could find in the store, hit it good and hot with a blowtorch to rob it of its temper, and drill a hole in the side to run the wires through :grin:




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