92 not running rite

J3ARB3AR

Registered User
I recently bought a 92 sc that suposedly has 10% overdrive pully kit, scp stage one cam, blue 38 pound injectors, a tunable scp chip, 80 mm maf. Again suposed to have all new sensor which i would agree they all look new that being the maf,cam,crank,tps,and o2 sensors. An supposedly the car has been tuned for these upgrades To fuel system and motor. Again this is all goin on what the previous owner told me and he gave me a lot of old parts like the old cam, old supercharger, old flexplate, intercooler, coilpack, water pump and sum other odds and ends. I just put new plugs in it an it already had newer wires along with new coil pack. So it used to have idle vacuum around 18in an would break sideways if i punched it at 15 mph so i ran it on the highway the other day honestly dont kno how fast i was goin the speedo doesnt go faster than 125 an we were still climing. Its an auto but i wasnt redlining it just was easing into throttle. So when we slowed down it was kind of chugging along an the vacuum was down around 10in. So this promted me to change plugs. Number 3 and 5 the elctrode one was broke off and the other was touching the pintle. So it has all new plugs and ive done compression test on all cylinders of which their all around 125 then we spark tested it an all the plugs are firing. I also sprayed brake cleaner all over the intakeand vacuum lines hoping for a change in idle and nothing changed. Now ive been babying it because i have to drive it about twenty minutes to work an if i get on it it always coughs around 3500rpms an will cough black smoke but it doesnt smoke at any other time, no blue,white or black smoke and whenever i take off even being easy the check engine light comes on for a few seconds then goes off. An the car is seriously down on power. It feels to me like a bad vacuum leak but we cant find one anywere i just have to find a day at work that i can smoke test it to be sure. So i need sum suggestions at this point. It has compression, it has spark, and if it coughs black smoke with bigger injectors im asuming its getting more than enough fuel. Im almost thinking about putting stock incjectors back in it but i dont want to waist money on somthing that probly wont make any difference. If u have any questions for me about the car i can answer to the best of my knowledge. But again im goin on what i can see an what the previous owner informed me of. Any advice much apriciated thanks guys
 
Last edited:
First thing. The blue injectors you speak of are #36 not #38. If it has been tuned to #36 then do not put the stock injectors back on. It will lean out and probably blow a head gasket.

Have you verified that the car does have a chip? The reason I ask is that you can cheat the system with a sampling tube change on the MAF to compensate for the larger injectors but this method does not work as well as a tune.

If the car ran strong when you got it I would bet something happened while you were on that high speed run. It concerned me that the ground electrode was missing on one plug and touching the center electrode on another. Something mechanical had to cause this. IMO.

What you describe sounds very much so like a vacuum leak but to be candid I believe something else is awry due to the plug damage.

I would start with a smoke test as you already completed a compression test. Get your vacuum leaks repaired.

No more sustained high speed driving. These engines get too hot as it is and unless you have a huge griffin radiator you are just pressing your luck.
 
This mite sound kind of dumb but how exactly would i verify that it has a chip. An ya the injectors are deffinatl baby blue in.color i was jus goin by what the guy told me but u never kno what all to belive when u buy a car that already is suposedly worked i honestly wish it was stock but i got it for a steal. So what if the smoke test doesnt find any leaks any other suggestion. Ive already pulled every wire off the coil one after another an the rpms changes an it misfires alot so i kno the plugs gota be firing an the bigger maf is deffiantly new its was to clean to have been in there awile an when i unplug it tha car almost stalls out so its reading. Ha an ya im not gona be running it like that for a long time even after i get this little bugfixe. Its gona sound stupid but i had to see what the thing could do atleast once but here again i didnt let it go over 4000rpms i was just easing into it not peddal to the floor
 
This mite sound kind of dumb but how exactly would i verify that it has a chip. An ya the injectors are deffinatl baby blue in.color i was jus goin by what the guy told me but u never kno what all to belive when u buy a car that already is suposedly worked i honestly wish it was stock but i got it for a steal. So what if the smoke test doesnt find any leaks any other suggestion. Ive already pulled every wire off the coil one after another an the rpms changes an it misfires alot so i kno the plugs gota be firing an the bigger maf is deffiantly new its was to clean to have been in there awile an when i unplug it tha car almost stalls out so its reading. Ha an ya im not gona be running it like that for a long time even after i get this little bugfixe. Its gona sound stupid but i had to see what the thing could do atleast once but here again i didnt let it go over 4000rpms i was just easing into it not peddal to the floor

You need to remove the passenger side kick panel and visually inspect the ECM to see if it has a chip attached.
 
Ya i just got done with the smoke test, no leaks from.what i could tell i had it running for about 20 mintues didnt see.smoke anywere. I will check for the chip when i get home tonite
 
How bout a slipped or streched timing chain that could cause the low vac an would.explain a mechhanical flaw that could messed up the electrodes on the plugs
 
Na just stock autolite plugs i cant stop shaking the feelin of the timing chain gettin stretched or jumped.teeth tho that could explain the low vacuum hesitation an damage to the plugs plus it would explain.why this started literally rite after i ran the car. An ya i checked them two days ago i guess when i did the compression check. The plugs have only been in since this past weekend to. Whats a good number for these.motors tho i got all cylinders rite around 125
 
Na just stock autolite plugs i cant stop shaking the feelin of the timing chain gettin stretched or jumped.teeth tho that could explain the low vacuum hesitation an damage to the plugs plus it would explain.why this started literally rite after i ran the car. An ya i checked them two days ago i guess when i did the compression check. The plugs have only been in since this past weekend to. Whats a good number for these.motors tho i got all cylinders rite around 125

Timing chain failures are extremely rare on these motors, but since the cam was swapped I suppose it's possible.

125 psi on all cylinders sounds fine. If it jumped time a couple teeth valves would be hitting pistons and bend the push rods or the valves. For the pistons to contact the spark plugs something would need to have gotten into the combustion chamber like a burnt off ground strap from the plug or a chunk of the piston. BTW Those injectors are barely big enough for a stock motor and I wouldn't be surprised it you ran it super lean and did some detonation damage. At this point I'd be pulling the valve covers and checking for bent push rods or a broken valve spring.

Knowing who you bought the car from might also be helpful.

David
 
Last edited:
Ya but the car is also running high hydrocarbons an all the other gases are in check so its gota be gettin enough fuel when i stomped on it befor this crap started happening it would spit a little bit of black smoke
 
Ya but the car is also running high hydrocarbons an all the other gases are in check so its gota be gettin enough fuel when i stomped on it befor this crap started happening it would spit a little bit of black smoke

If you believe that high hydrocarbons during part throttle emission testing and some black smoke coming out the tail pipe when first stomping on gas pedal, means you have plenty of fuel at wide open throttle....your assumption is false.

David
 
Ok so asuming the motor is mechanically ok i should try bigger injectors or atleast have it retuned? Cause in another step or two im about to just take it to a dealer cause this older guy in my shop has been helpin me here an there but we dont have a lota time to fool with it being on the clock an i dont have the resources at my house to do anything with it an were about all outa ideas expect posibly stretched timing chain not that it jumped teeth but after the pull it mite have done somthing cause it started doin this like instantly after the running it hard
 
Ok so asuming the motor is mechanically ok i should try bigger injectors or atleast have it retuned? Cause in another step or two im about to just take it to a dealer cause this older guy in my shop has been helpin me here an there but we dont have a lota time to fool with it being on the clock an i dont have the resources at my house to do anything with it an were about all outa ideas expect posibly stretched timing chain not that it jumped teeth but after the pull it mite have done somthing cause it started doin this like instantly after the running it hard

First you need to figure out what is wrong, then try to determine what caused it, then fix it. Fixing it might or might not include upgrades to the fuel system and retuning. Can't give you a reasonable answer until you figure out what is wrong with it now.

David
 
Ok so asuming the motor is mechanically ok i should try bigger injectors or atleast have it retuned? Cause in another step or two im about to just take it to a dealer cause this older guy in my shop has been helpin me here an there but we dont have a lota time to fool with it being on the clock an i dont have the resources at my house to do anything with it an were about all outa ideas expect posibly stretched timing chain not that it jumped teeth but after the pull it mite have done somthing cause it started doin this like instantly after the running it hard

Or a bad vacuum leak.

I agree with Dave. Figure out what is wrong first. Hey if you have time and money to burn then take it to the dealer and be prepared to get raped. Even back in the day when these cars were new the dealers sucked at diagnosing issues. Now that the last one rolled off the assembly line almost 20 years ago, good luck finding a tech at a Ford dealer that even worked on one of these cars before. Any of the tech's that did are gone and most of them were confused by these cars anyway. Just my .02 worth. There are plenty of knowledgeable people on this board you should try listening to some of us. :)
 
Timing chain failures are extremely rare on these motors, but since the cam was swapped I suppose it's possible.

125 psi on all cylinders sounds fine. If it jumped time a couple teeth valves would be hitting pistons and bend the push rods or the valves. For the pistons to contact the spark plugs something would need to have gotten into the combustion chamber like a burnt off ground strap from the plug or a chunk of the piston. BTW Those injectors are barely big enough for a stock motor and I wouldn't be surprised it you ran it super lean and did some detonation damage. At this point I'd be pulling the valve covers and checking for bent push rods or a broken valve spring.

Knowing who you bought the car from might also be helpful.

David


You know Dave I didn't even think of a bent pushrod or busted valve spring until I read this post. it makes a ton of sense especially after a sustained high speed run. That would certainly not affect compression at all but would make it run like total crap. I like the valve train suggestion a lot.
 
Or a bad vacuum leak.

I agree with Dave. Figure out what is wrong first. Hey if you have time and money to burn then take it to the dealer and be prepared to get raped. Even back in the day when these cars were new the dealers sucked at diagnosing issues. Now that the last one rolled off the assembly line almost 20 years ago, good luck finding a tech at a Ford dealer that even worked on one of these cars before. Any of the tech's that did are gone and most of them were confused by these cars anyway. Just my .02 worth. There are plenty of knowledgeable people on this board you should try listening to some of us. :)

Ha ya id love all the advice i could get thats why im on here now. So looks like im pulling the valve covers this weekend lol but u guys would cross the timing chain off the list an go with valve train instead?
 
An ya i wanted it to be a vacuum leak so bad but i.smoke tested it the other day for lil over 20mins an never saw a trace of smoke anywere
 
Ya it will come on somtimes for like a minute or so after i take off then goes off. I tried hooking it up to the genesis but the contacts outa the car are dirty i jus need to clean them up a little then hook it up again
 
Run those codes

You have to run those codes. Electrical will cause all kinds of problems So go through and inspect all the electrical connections you can. Clean the grounds. I would highly doubt a timing chain issue. I have looked for compression specs but couldn't find any. 125 psi sounds low but they are all equal so I also doubt that is a problem. Of course these motors are low compression so 125 might just be fine.
 
Back
Top