Engine 87 LX won't run after warmed up

gtboost02

Member
Nov 27, 2020
5
3
13
60
bolivar,pa.
hello all, i'm new to the site but have been into fox bodies a long time. here's the short description of my issue: i'm putting an 87 LX together from a shell. the car will start when cold with the idle being terrible, then when it warms up it just stalls out even with me riding the the throttle. when i first got it running and i drove it a couple miles it pulled hard and ran strong, but never could get a decent idle out of it. iv'e tried alot of the basic testing & what i think would be a possible suspected items. including swapping out the computer as well as the whole distributor and tps. has anyone had this problem before?
 
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Haste347

Member
Oct 6, 2020
9
3
13
44
Houston
Have you gone through the checklist of verifying the idle w/o the IAB plugged in, TPS voltage, etc? 87's don't have mass air sensors, so they are more particular about the TPS being right. This also might have something to do with the o2 sensors as the cpu goes into closed loop after warm up.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
19,330
6,426
193
polk county florida
Several things can cause this, I would go through the 'surging idle checklist', you may discover multiple issues since this sounds like it's been put back together and you didn't acquire it already running,
This will show you the proper procedure to test sensors and check for codes, set idle and other things. Do the list step by step, don't skip around, the next step depends on the one before, it also keeps you from chasing you tail and just repacing random parts hoping to resolve the problem(s).
There are lots of info in the technical/how thread in the sticky section in the tech forum where experienced members have been there done that and show how to fix it.
 

gtboost02

Member
Nov 27, 2020
5
3
13
60
bolivar,pa.
sorry to say, it WAS converted to mass air by someone previously. i'm going to check for codes, that's one of the only things on that list i didn't go through. i'm also going to try an old school thought and change the coil out. i did most of the other tests. ALSO it was smog deleted as well. i'm sure of one thing by the way it ran when i first got it running it not a cracked piston or stuck valve.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
19,330
6,426
193
polk county florida
. i'm going to check for codes, that's one of the only things on that list i didn't go through. i'm also going to try an old school thought and change the coil out. i did most of the other tests.
This tells me you didn't do what the directions stated in the checklist.
Look, with the problems this car has you have your hands full so you have to be methodical in diagnosing all the issues because believe me, you have a few.
 

Decipha

Active Member
Aug 22, 2007
215
37
39
New Orleans, LA
www.efidynotuning.com
pinched fuel line will restrict fuel flow and cause lean out at wot which is the #1 cause for engine failures and a perfect way to grenade the engine

hence why you should never go WOT when you have mechanical problems or if the vehicle is not running correctly. As you stated it pulled hard that was guaranteed to be damaging the engine ever time you got on it.