glowing exhaust
11-03-10, 01:43 PM
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glowing exhaust
90 gtu bought the car and the oil pan/ front cover gasket were leaking replaced both of them, started it up and my cat started glowing. so i replaced the exhaust and i had the same problem i corected my timin installed plugs wires o2 sens fuel filter checked fuel pressure it was all good, and the exhaust is still getting really hot, im told a glowing exhaust can either be a bad cat or a lean condition, but the cat is brand new so i figure its lean i cant find any vaccum leaks and no one has been able to help me out, just lookin for ideas please help!
11-03-10, 01:54 PM
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You still running emissions? Have an AFR gauge? Idling fine? Need more info.
NORMALLY it is the cat and/ or lean conditions (both, usually), but if variables a' 'b' and 'c' are taken care of, then more info is needed to help diagnose.
NORMALLY it is the cat and/ or lean conditions (both, usually), but if variables a' 'b' and 'c' are taken care of, then more info is needed to help diagnose.
11-03-10, 02:32 PM
#5
90 gtu bought the car and the oil pan/ front cover gasket were leaking replaced both of them, started it up and my cat started glowing. so i replaced the exhaust and i had the same problem i corected my timin installed plugs wires o2 sens fuel filter checked fuel pressure it was all good, and the exhaust is still getting really hot, im told a glowing exhaust can either be a bad cat or a lean condition, but the cat is brand new so i figure its lean i cant find any vaccum leaks and no one has been able to help me out, just lookin for ideas please help!
11-03-10, 02:52 PM
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no lean conditions will cause very high exhaust temp. the car runs pretty damn good aside from the high exhaust temp but i cant for the life of me figure it out, im gonna start messing with my tps when i get off work. i would love any ideas that could help me out
11-03-10, 03:37 PM
#7
When a car runs rich all the fuel is not ignited by the plugs so the fuel that isn't combusted ends up doing so in the exhaust which causes the high temperatures. Lean conditions can cause your problem but it's more likely at full throttle as opposed to idling. You need to check the timing, see if your plugs are firing properly especially the leading plugs and also check your compression as a blown apex seal can cause this problem as well.
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11-13-10, 10:37 PM
#8
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i did a compp check it seemed good. but my plugs smelled alot like fuel, im thinking im running rich i know im getting spark, but what else can cause this im really stumped!
11-13-10, 11:14 PM
#9
When checking the timing it means more than just checking for basic spark. Look at post #99 and so on in the link below for an easy to understand illustration. Higher than normal fuel pressure might lead to an overly rich condition as well.
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/86-tii-swap-wont-start-but-really-wants-887302/page4/
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/86-tii-swap-wont-start-but-really-wants-887302/page4/
11-14-10, 09:38 AM
#11
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Yeah, you probably have your timing way off.
The 'Stab" method for the CAS never works.
This is the post that Satch was telling you to look at.
The 'Stab" method for the CAS never works.
This is the post that Satch was telling you to look at.
Go turn your front pulley til the first mark on the pulley is opposite the fixed pin on the front cover.
Now look at my jpg attached of the CAS without the top cover. YOURS should look the same. The SAME means the two teeth on the top of the rotor in the CAS should cut across the corners of the two black pickups I show in my picture.
IF yours looks like my picute, then the timing should be well within what's required for starting the engine.
Now look at my jpg attached of the CAS without the top cover. YOURS should look the same. The SAME means the two teeth on the top of the rotor in the CAS should cut across the corners of the two black pickups I show in my picture.
IF yours looks like my picute, then the timing should be well within what's required for starting the engine.
11-14-10, 11:27 AM
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yea i looked it up when i installed my cas i just stabbed it in there and used a timing light. gonna take of the cover and check it out after work i will be so happy if thats my problem!! running waaaaay toooo riiiichh! thanks guys
11-14-10, 11:34 AM
#13
the S5's are far more touchy about setting timing than the S4's, they need to meet more requirements before the timing will be ready to set to base timing, unlike the S4's which you can basically just idle down to below 1k RPMs and they automatically use the base timing map figure.
and yes, running rich will cause the exhaust to glow, not the other way around while out of load. check timing, fuel pressure, TPS adjustment and check for vacuum leaks with a can of carb cleaner.
and yes, running rich will cause the exhaust to glow, not the other way around while out of load. check timing, fuel pressure, TPS adjustment and check for vacuum leaks with a can of carb cleaner.
11-15-10, 10:28 AM
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well i just set it like in the picture and i started it up and it wont idle lower than 2500 rpms and now theres just a tiny spot on my cat that is glowing. but i cnt get idle lower. im wondering what else to test!
11-15-10, 10:47 AM
#17
The idle probably had to be set abnormally high to get it to idle with the timing that far retarded. Now being set closer to where it should be it will idle very high. And all the fuel being burnt in the exhaust due to the timing problem may have nuked your cat causing it to be blocked by it's own fill, thus causing a hot spot....
Just a possibility.
I would take the cat off, for inspection, and put in a straight pipe and get the car running properly before putting the cat back on.
Just a possibility.
I would take the cat off, for inspection, and put in a straight pipe and get the car running properly before putting the cat back on.
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