So ive been having a problem with my 86 gxl. I thought my problem was the 3800 hesitation. But im thinking its something else. So here is the problem, when i go and drive the car it only goes up to right around 3000 rpm then gets louder and has a very hard time gaining more speed/ rpm. then when i let off it backfires. The problem is only under load. it free revs very nice. when the problem happens it feels to me like a fuel cut. At one point i took off the intake and checked both primary and secondary injectors. They were both priming the system. After all this i thought it could be my ports. so i ghetto wired them open just to see if that was the problem. it was not. Grounds are good. any help would be great.

When I pulled the motor from my S5 it was having the same problem...

do you have any idea what it is?

From the sounds of it, limp mode is your problem.

Im not sure the S4 has limp mode capabilities.



This is a tricky one. See if your cats arent glowing red hot first.

I would then take some Vac readings, and also see if its steady.

so check vacume? there is no cats. the exhaust is open right now after the manifold. so yes the ports would not be working.

Your ports arent working so youll run uber rich while the motor is expecting more air from the 5th/6th ports opening. If you can route exhaust to your 5th/6th port actuators youll be golden.

He said he wired them open so I discounted that as a possibility. But I agree, that's what it sounds like the problem is.

yeah, when i wired them open there was no change. the only thing it changed was it wanted to die out while it was idleing. but under load no difference

its one of two things.



1. the secondary injectors are not coming on



or the throttle position sensor is bad

it could be the TPS. the secondarys prime. so im assuming they open up. if it is the tps do you have a link on how to adjust or fix it?

secondaries prime? what does that mean?



look in the FAQ or the FSM (google!) for the tps, its the big problem with the s4's

a few months ago i pulled off the intake and left the rails hooked up. when i turned the key so the motor would try to start. the secondarys would spray.

ok, that at least means the injectors work, and the wiring is ok.



they are supposed to come on about 3500rpm, without em it leans out very fast, it is a fuel cut basically

the car does feel like a fuel cut thou. the car gets very loud and wont really pick up speed. hesitates while getting louder and louder then when you let off it backfires. would that be a TPS?

i think so, when they get really bad, the ecu does weird things. its super easy to check, shop manual is online.

ok, ill give that a try. https://www.nopistons.com/forums/pub...>/bigthumb.gif thanks for the help. ill fill you in if that fixes it.

I had a problem with my car kinda like that. The car would drive just fine, but anytime I tryed to put a load on the engine I could hear the turbo try to spool the engine would get loud. It would back fire and go no where fast..



Me problem ended up being faulty primary coil wiring....(just a idea?)