trying to diesel

88Supraboy · 11-01-2005, 12:14 AM

when i turn my 88 n/a off it will keep running for a few seconds then shut off, even with the ignition off and key out. I know overheating can cause this but its not hot at all, it will even do it when dead cold. Ive also re-checked my timming and its still around 12 degrees advanced. just wondering if anybody has experienced this or know what to fix.

Thanks Supra Lovers!!

Bullz_EyE · 11-01-2005, 02:32 AM

That's weird. I thought dieseling was only subject to carbureted vehicles because fuel gets shut-off when the ignition is off. You may want to try a bottle or two of strong fuel system cleansers and see if problem persists.

SupraMan1784 · 11-01-2005, 01:49 PM

where are your rpms at idle? and do you hear any other noises?

rnoswal · 11-01-2005, 02:06 PM

Sounds like a leak in the injector, or one that is not spraying right. Also there could be a lot of carbon buildup on the piston top. The combination of fuel not being burned completely and soaking the carbon on the piston could keep it running a little bit longer. The carbon stays hot and ignites the fuel even without a spark.

They make cleaners for that purpose at the parts houses, but sometimes the carbon is very hard and takes a wire brush. Just my guess though.

Russ

supra_91 · 11-01-2005, 02:44 PM

get some seafoam. you can find it at any auto parts place or even walmart for that matter

this stuff works really good

Burn N' Up · 11-01-2005, 09:19 PM

Even though it probably won't help your specific problem every car can use a good seafoaming once in awhile. seafoam is good stuff. Maybe your fuel shut off? or your fuel pressure reliefe valve? if its not dumping fuel will continue to spray for a few moments into the engine, that is all assumeing that it is hot enough to combust though....

joel w · 11-01-2005, 10:08 PM

agreed with the above mentioned. but also try to retard your timing back a bit, your too far advanced possably, That 12 degrees you mentioned is that with the diagnostic timing jumper installed? set it to 10 degrees with the jumper installed, you may want to pull your upper timing belt cover and double check that the cam marks are in the corect position when its TDC on #1 and the timing marks at 0

mrnickleye · 11-02-2005, 04:07 AM

When the key is off, the ECU stops sending signal to injectors. So...if injectors are not leaking, no residual pressure will cause fuel to enter the engine. In fact, fuel pressure should remain in the rail after engine is off.

Carbon on the piston tops will glow hot enough to light fuel vapors after key is off. Run a couple of bottles of TECHRON thru your fuel tank, as directed on the bottle. (Walmart has the best price at $5.95 ea) This is good to do every 2-3 months anyway.

If 1 or 2 injectors were sticking open a little bit, you would likely notice some running problems, and hard start, as the fuel pressure would have dropped to zero, and those cylinders would be flooded. But I doubt even 2 sticking injectors would cause "after run".

Perhaps the cold start injector, which would be the only one common to 'all' the cylinders, is stuck open a tiny bit. It would allow the fuel pressure to drop and possilbly cause your problem. The 02 would see the extra richness, and adjust the regular injectors down a bit to get the good mixture during running condition.

Keep us posted.

88Supraboy · 11-03-2005, 02:20 AM

wow! thanks for all your ideas!! this fourm is awesome.

I dont think its carbon build up, i use cleaner very often, and probley not from heat either, it will do it if i just start it up after all night, then turn it off. I'm thinking its something to do with fuel pressure or an injector(s) but it runs fine and pulls hard (like all supras). also when i start it, it will turn over for a few seconds before starting, but not much to worry about.
and with the timing, i just used a normal timing light, and runs fine at +12, no valve knock or anything.
Thanks again everybody, its nice to have others that care about our supras as much as we do.

11-01-2005, 01:49 PM	#3
SupraMan1784 SP58GT Join Date: Jun 2005 Location: Dirty Jerz Posts: 691	where are your rpms at idle? and do you hear any other noises? __________________ Now: Saving for an MKIV Broken Rides: (Sold) 91 supra turbo 5speed with a 1jzgte motor 421whp 400(399) ft*lbs of torque on tap @ 15 psi "Always outnumbered, never outgunned."

11-01-2005, 02:44 PM	#5
supra_91 Lexus & 550's Join Date: Sep 2005 Location: Illinois Posts: 521	get some seafoam. you can find it at any auto parts place or even walmart for that matter this stuff works really good __________________ 91 N/A automatic supra;K&N FIPK;2.5" custom exhaust;no cat;pacesetter header;eibach springs;tokico "blues";MKIV TT rims

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11-01-2005, 12:14 AM	#1
88Supraboy 3" Exhaust Join Date: Oct 2005 Location: Michigan Posts: 55	trying to diesel when i turn my 88 n/a off it will keep running for a few seconds then shut off, even with the ignition off and key out. I know overheating can cause this but its not hot at all, it will even do it when dead cold. Ive also re-checked my timming and its still around 12 degrees advanced. just wondering if anybody has experienced this or know what to fix. Thanks Supra Lovers!!

11-01-2005, 02:32 AM	#2
Bullz_EyE 3" Exhaust Join Date: Oct 2005 Location: San Diego, CA Posts: 238	That's weird. I thought dieseling was only subject to carbureted vehicles because fuel gets shut-off when the ignition is off. You may want to try a bottle or two of strong fuel system cleansers and see if problem persists.

11-01-2005, 02:06 PM	#4
rnoswal Lexus & 550's Join Date: Apr 2005 Location: Bossier City LA Posts: 556	Sounds like a leak in the injector, or one that is not spraying right. Also there could be a lot of carbon buildup on the piston top. The combination of fuel not being burned completely and soaking the carbon on the piston could keep it running a little bit longer. The carbon stays hot and ignites the fuel even without a spark. They make cleaners for that purpose at the parts houses, but sometimes the carbon is very hard and takes a wire brush. Just my guess though. Russ

11-01-2005, 09:19 PM	#6
Burn N' Up 3" Exhaust Join Date: Sep 2005 Posts: 238	Even though it probably won't help your specific problem every car can use a good seafoaming once in awhile. seafoam is good stuff. Maybe your fuel shut off? or your fuel pressure reliefe valve? if its not dumping fuel will continue to spray for a few moments into the engine, that is all assumeing that it is hot enough to combust though....

11-01-2005, 10:08 PM	#7
joel w Lexus & 550's Join Date: Aug 2005 Location: In the shadows Posts: 506	agreed with the above mentioned. but also try to retard your timing back a bit, your too far advanced possably, That 12 degrees you mentioned is that with the diagnostic timing jumper installed? set it to 10 degrees with the jumper installed, you may want to pull your upper timing belt cover and double check that the cam marks are in the corect position when its TDC on #1 and the timing marks at 0

11-02-2005, 04:07 AM	#8
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	When the key is off, the ECU stops sending signal to injectors. So...if injectors are not leaking, no residual pressure will cause fuel to enter the engine. In fact, fuel pressure should remain in the rail after engine is off. Carbon on the piston tops will glow hot enough to light fuel vapors after key is off. Run a couple of bottles of TECHRON thru your fuel tank, as directed on the bottle. (Walmart has the best price at $5.95 ea) This is good to do every 2-3 months anyway. If 1 or 2 injectors were sticking open a little bit, you would likely notice some running problems, and hard start, as the fuel pressure would have dropped to zero, and those cylinders would be flooded. But I doubt even 2 sticking injectors would cause "after run". Perhaps the cold start injector, which would be the only one common to 'all' the cylinders, is stuck open a tiny bit. It would allow the fuel pressure to drop and possilbly cause your problem. The 02 would see the extra richness, and adjust the regular injectors down a bit to get the good mixture during running condition. Keep us posted.

11-03-2005, 02:20 AM	#9
88Supraboy 3" Exhaust Join Date: Oct 2005 Location: Michigan Posts: 55	wow! thanks for all your ideas!! this fourm is awesome. I dont think its carbon build up, i use cleaner very often, and probley not from heat either, it will do it if i just start it up after all night, then turn it off. I'm thinking its something to do with fuel pressure or an injector(s) but it runs fine and pulls hard (like all supras). also when i start it, it will turn over for a few seconds before starting, but not much to worry about. and with the timing, i just used a normal timing light, and runs fine at +12, no valve knock or anything. Thanks again everybody, its nice to have others that care about our supras as much as we do.