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1992 sputter at high rpms

3620 Views 16 Replies 4 Participants Last post by  92lxguy
The only time it will do it is when I get up to 3000-4000 it almost acts like its loading up on fuel. I have put new o rings and pintle caps on the injectors, new fuel pressure regulator, new plugs wires cap and bitten 3 months ago. I just don't know what else to do.

Mods are edelbrock performer rpm ii, gt40p heads, e303 cam, Bbk cold air
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GT40P head... did you upgrade the springs?
GT40P head... did you upgrade the springs?
They were already on the car when I bought the car. how would I know if they are upgraded springs?
Sorry I don't mean to sound stupid.
Sorry I don't mean to sound stupid.
Bro, I'm an amatuer myself. I just try to help people when I can. The reason I ask is because the stock springs on the GT40P head can't handle a Mustang stock cam let alone an aftermarket cam like you have. Many people have experienced a 'miss' or 'stutter' at higher RPM's after a GT40P head swap because they did not upgrade the springs to be able to handle the increased lift. Has the car done this since you owned it or is it a new problem? If it's a new problem, this probably isn't the case. If this problem has been since you've owned it, it is a possibility. I'm not sure how you'd identify aftermarket springs. Maybe one of the more well versed folks can help you out. Secondly, is your check engine light on? May as well check out all your problems in one fell swoop and get her running right so you can take her out again.
when i bought the car it was running really rich so i found that the timming was way off and no t stat then it didn't run bad but it started to lay down in 3rd so i put a new fuel pump and changed the gas tank couse the baffles were broke in the tank still had the laying down problem. it had bigger fuel rails on it and i didn't be leave that it was hooked up right so i decided to go back to stock when i did that i found out the pintle caps were broke on the injectors so i fixed that and put a new fuel pressure regulator on it now it don't lay down it just sputters between 3000 and 4000 some times does it when i first start it and take off.
Bro, I'm an amatuer myself. I just try to help people when I can. The reason I ask is because the stock springs on the GT40P head can't handle a Mustang stock cam let alone an aftermarket cam like you have. Many people have experienced a 'miss' or 'stutter' at higher RPM's after a GT40P head swap because they did not upgrade the springs to be able to handle the increased lift. Has the car done this since you owned it or is it a new problem? If it's a new problem, this probably isn't the case. If this problem has been since you've owned it, it is a possibility. I'm not sure how you'd identify aftermarket springs. Maybe one of the more well versed folks can help you out. Secondly, is your check engine light on? May as well check out all your problems in one fell swoop and get her running right so you can take her out again.
and i don't have a check engine light any more couse i bought a set of gauges from fl 5.0 that replaces the stock cluster. i pull the codes and its for the smog stuff that is no longer there my car is a 4cyl swap that was done before i bought it
With all that you stated was wrong with it sounds like a shade tree mechanic did the work. I wouldn't be surprised if the heads were put on there with the stock springs, too. Anyone else want to chime in and give this fella more of a hand than I can?
Come please someone give me something. Thanks David for the help
if i unplug an injector the car should sound like its missing real bad right?
Never mind I figured it out it was the Maf sensor
glad you checked the maf . I had the same problem and thats what it was
Weird that you pulled the codes and nothing popped for the MAF. Glad you found the problem, though! Good luck!
How do you check the maf? I have sputter or ping at 4k...thinking its some of the above issues or the fuel filter.
How do you check the maf? I have sputter or ping at 4k...thinking its some of the above issues or the fuel filter.
I took my buddys out of his car and tried it in my car. Is you car running rich and does it smoke at 4k?
No sir, there is no smoke at all. We had it on the dyno last week and heard it in 4th gear. we stopped when we heard it. Car still made 222rwhp and 282 torque.
No sir, there is no smoke at all. We had it on the dyno last week and heard it in 4th gear. we stopped when we heard it. Car still made 222rwhp and 282 torque.
with mine it would brake up real bad at about 3000 to 4000 if i held it there at like 3500 and then stand on it it would huff black smoke
this might help you some i found it on another forum



On my 95 the pre-oiled air filter caused my MassAir to get "dirtied" up. Watch how much oil you put on the filters. Due to the oil being sucked off the filter the two little wires in the MA were dirty and threw the EEC a curve ball which led to a lean condition and knockin/pingin at 4500-500RPM. Once clean everything was perfect.
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