damn, i guess it can't be all good

jd20phill

Member
Jun 2, 2005
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Little Rock, Arkansas, United States
alright, i'm driving home, i give it a little gas, turbo spools up, everything seems fine. After i let off the gas, the car starts missing like crazy, to the point where it won't even idle. I get it home like this, check the codes, and there is nothing new. The car has always thrown a code 24 (Intake air temp sensor) but with no ill effects, and that is the only one it is throwing now. It started running really rich after all this happened. I'm thinking maf, but before i invest in another, do you guys have any ideas what is a matter. thanks in advance and sorry for the long post.
 

jdub

Official SM Expert: Motor Oil, Lubricants & Fil
SM Expert
Feb 10, 2006
10,730
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Valley of the Sun
Test your coil packs per the TRSM:
http://www.cygnusx1.net/supra/library/TSRM/ig/IG_12.html

You may have had one fail. Also things to consider: plug wires, plugs, ignition module.


jd20phill said:
would that cause it to miss really bad? I mean, it misses at idle and all the way through the rpm range. I know a blown hose would make it run rich, but would it act like it is running on 4 cylinders?
 

jd20phill

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Jun 2, 2005
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could the timing belt have jumped a gear on the camgear?. I'm looking at them and it looks like it is about a tooth off. i unplugged the afm, and it changed nothing. Just pulled all the plugs and they looked fouled. I don't have a spare maf sitting around. I tested it via tsrm, and only got resistance (1500) between the two outside prongs on each side. I couldn't get any from the center though. ???
 
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lagged

1991 1JZ
Mar 30, 2005
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while its idling unplug the AFM. if it idles good with it unplugged but idles like shit with it plugged in, the AFM is bad. i would still go check for a boost/vacuum leak. all ic hoses and vacuum lines.
 

lagged

1991 1JZ
Mar 30, 2005
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new rochelle
it would cause the car to run like garbage. since you said it happend while you you were boosting and is still doing it, im still gonna have to go with boost leak... look harder.

clear codes, drive the car again and pull codes again and post back.
 

jd20phill

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Jun 2, 2005
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Little Rock, Arkansas, United States
ok, i pulled all of the intercooler hoses, they needed to be replaced, so i ordered them. They should be here in two weeks. For the time being i inspected the old ones really well, put the old ones back on, and tightened them really well. The car still runs like crap. Checked the coded, still the same. I unplugged the idle control valve (the black thing on the intake manifold), and i got it to idle. Unplugging the afm has no effect. Changing the oxygen sensor helped a bit. It still acts like it's missing though. Is it possible that the timing belt slipped and is off a tooth on the cam gears? the car is pushing a lot out of the tailpipe (can feel the air 6ft back), which is what my non turbo was doing when it was out of time(b/c of distributor). Before i go messing with the timing belt, i want to know if it being only a tooth off could cause my car to run like complete ass. Could the cps also be at fault? Any imput is appreciated.
 

NATAN666

yarrrrr
Apr 4, 2005
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a boost leak wouldnt screw up idle man.... uness it was HUGE... im thinking ignition electronics. check and replace everything if neccesary... make sure your CPS (cam position sensor) is functioning properly as well.
 

jd20phill

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Jun 2, 2005
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Little Rock, Arkansas, United States
ok, i checked the wires and the timing is dead on. Could the cps be out? the car barely runs. It acts like one of the cylinders isin't firing and sounds like it has a really bad exhaust leak (it doesn't though). I guess that's because of the dead cylinder. What would a dead cps do? Wtf is the deal?
 

johnathan1

Supra =
Aug 19, 2005
5,056
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Downey, California, United States
check the coupler that connects the 3000 pipe to the throttle body... and start spraying around with carb cleaner...

It is also definitely possible that it is the igniter, just doesn't seem likely...

How's your accordian hose? BOV hoses and vac lines?
 

suprajonny

New Member
Mar 28, 2006
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Wilmore, Kentucky
If the car misses at idle check the following:
-plugs and plug wires for damage or short cicuits
-sticking or faulty emissions sys.
-Clogged fuel filter
-Vacuum leaks at the intake manifold or hose connections
-cylinder compression could be low or uneven across all cylinders
-fuel injectors could be clogged
-throttle body could be dirty or clogged

If I read your post correctly the car is running rich and missing excessively at idle speeds. That will have nothing to do with the turbo. The major systems involved in engine operation at idle speeds are going to be your fuel and ignition probably. When you checked the plugs what did they look like?
 

jd20phill

Member
Jun 2, 2005
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Little Rock, Arkansas, United States
well, the plugs were black, but that was because it ran really rich when it started missing. It just acts like it's out of time. THe thing of it is though is that the cps, the cam gears, and the motor are all where they are suppost to be? If the cps goes bad, could the car still run? I know it wouldn't run well, but would it run at all. The car won't even stay running now. Besides a compression test, how could one tell if the motor had lost compression?
 

johnathan1

Supra =
Aug 19, 2005
5,056
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Downey, California, United States
does the car overheat too? lost any coolant? I haven't heard a story of a Supra not being able to idle because of a BHG... Doesn't seem likely that the cylinders are losing compression... I'm telling you that it sounds like a vacuum/boost leak, my car was leaking at the throttle body > int. manifold gasket, as well as at the lower intake mani > head [gasket]...and it wouldn't idle AT ALL w/out revving to 2k RPMs... Sounded and felt like the car was running on 2 cylinders or was WAAAY out of time. When you rev the engine does it seem like it running okay.. ie: no missing?... or does it run crappily at higher engine speeds as well?