1986 N/A wont rev past 4,000RPM
 

Iys really wierd i dont know if its because of spark or fuel but it runs fine all the way to 4K and then looses all power new fuels filter plugs and wires have all been replaced since this started... after the plugs it fixed it for a whije vyt after ir sat for a week it started agian could my plugs by fouled again maby?? or maby a fuel pump??? please help

sounds like your car is in limp mode, maybe check your tps. do a search for limp mode and you should find things to check.

This has been answered in the FAQ.
3,500 - 4,000 RPM Hesitation.


I have this hesitation whenever I accelerate right around 3500-4000 RPM
The dreaded 3800 RPM hesitation is cause 90% of the time by poor ground connections between the engine, the battery, and the car. Clean or replace all the under hood ground connections. On 86 model year cars , replacing/regrounding the pressure sensor's ground wire has helped (do not re-ground a 87 or later model year). If there is still a problem after that, look at cleaning the fuel injectors and (on a N/A) that your 5th/6th ports are operating correctly. - Icemark

my car does something similar its right at 3500 rps though as soon as it hits it goes right back to 1000 and wont stop the only other thing i havent seen anybody else say is for about 3 mins after start up thick blue smoke pours out of the exhaust but heres the mods i have a 13b N/A and ive replaced the wires the plugs the fuel pump and filter has been replaced and the injectors have been cleaned and i cleaned the MAF sensor could some one send me a link for a DIY or some help for this please its been happening for about 3 months and im ready to scream

lol (bangs head)

S4s don't have limp mode.

What he's describing is not a hesitation; it's a full on wall he can't get past. It sounds more like the secondaries are not even coming online, which would completely starve the engine for fuel at and above the transition point.

Yeah I hit a wall at 3500 it will not go past it no matter what I do and I'm lost as what to do

your cat's are probably plugged. This happened on my fc and the first converter had imploded and collapsed into the second. I took them off and gutted them.

I put my 7 on the road like 2 weeks ago and i get this problem from time to time and i have no cats. Mines an 86 so im going to try and reground the pressure sensor and clean up the rest of the grounds.

Make sure your auxiliary ports are opening too.

I had this exact problem today, but after driving my car with no problems, I started it up later and she wouldnt rev past 2k even though I was down 50-60% on throttle. Got under the hood and looked at my tps, one of the plungers was stuck and there was a huge gap between it and its lil' cam.

Freed it up with my hand and it ran fine. Or you could just have a problem with the sensor itself.

When it happened I was thinking it was in limp mode myself, but there was no check engine light.

thats the wierd part about my car my CEL isnt on it hasnt come one since i got the car but its functional soo im lost as to what the problemis im thinking vacuum cause everything on that car is oem and its got 157k miles the hoses and everything have got to be toast by now

my car did that before , it was just an injector plug that had come loose , plugged it back in and it was back to normal

yeah my car has done the same thing. i just took out the tps plug and cleaned the contacts, and it ran great! try looking at your all connectors and making sure theres no corrosion.

i'd definitely check the auxiliary ports (just take them off and use a zip-tie to keep them open). You could also have a problem with your fuel injectors, those suckers may need to be cleaned out.

Auxiliary port problems would not cause a wall or even much of a hesitation, but you would feel a loss of top end power. It sounds like your secondary injectors are not coming on at all. Can you free rev above 4k? Have your injectors ever been cleaned?

The only thing that would cause a brick wall at that point is the secondaries not coming online. If the aux ports aren't opening you'll still make power. It just stops rising and quickly starts falling off but doesn't stop making it completely. I had an old 2nd gen ecu that was fried internally. The secondary injector drivers were shot. At around 3600 rpm (ish), the car fell on it's face. It would not go past that point at all.

i have a question.. dont mean to intrude.. but why wouldnt you want to reground an 87 or later if its the same problem?:dunno:

My '87 NA it hiting a brick wall at about 3500 RPM. Not loseing power, just not able to go any higher on RPM. When I test drove the car, the owner was freaked when I took the car over 2800. Now I know why. I am going to run two tanks of injector cleaner in hopes that it will do the trick. I already unseized the port actuators, and purchased injectors, just haven't replaced them yet.

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Go to the two secondary injector connectors and pull 'em off. Key to ON. See if one wire in each connector has batt voltage or not. Should. Sounds like one of the two is off the injector.

Or driver the car using little pedal until you reach 5000rpm. Should. Then stomp the pedal at 5000 and see what happens. IF the engine starts acting crummy with light throttle and reaching appox 3500-3800 rpm.........then suspect the boost sensor is not seeing vacuum from the engine.

And or go to the ECU small plug and make sure each of the four light green wires have batt voltage with the key to ON. Check at the plug, not the jack on the ECU. If you get batt voltage at each light green wire on the small ECU plug, the wiring is intact for each of the injectors.

Then go to pin 2B and make sure it has 3.5-4.5vdc with the key to ON, engine off. 2B is the middle ECU plug and the counting is from looking into the wire side of the plug in a up/down fashion. 2B would then be on the lower row......far right. Brown/red wire.

See what happens... The engine almost overheated...... Long story short, I took the 7 to a garage on Saturday to have the split air pipe welded, I figured it wouldn't hurt to have all the fluids dumped and replaced, including the coolant. When they re-attached the neck over the thermostat, they eitehr didn't replace the seal, or didn't tighten it down enough. Either way, I'm pissing fluid. They also tore up the seal on the bleader screw. Shop is going to re-emburse me for all of the work they did, still pisses me off. SO, after I repalce the seals (and thermostat for good measure) I'll get back to testing.

Thanks for the pointers!

BTW, anyone know where I can get another bleader screw?

[QUOTE=RotaryRocket88;9115743] S4s don't have limp mode. [QUOTE]

when i saw him post limp mode, i was like wtf??

Missed the "/" in the closing [quote] tag.

Something is wrong, I can't get the RPM over 4000 in or out of gear. I started to look at the injectors and noticed that I can move the top forward injector by hand. I shouldn't be able to do that... should I? the top rear injector doesn't budge at all.

I'm about ready to pull my UIM and LIM off and replace the injectors and see what other disasters I can find.

im having the same problem! no power over 4000rpms. Or at least not pulling to redline. gonna clean out the aux ports and clean up the grounds sometime this week. ill post with results. hopefully the results will help us out.

mine is a 86 gxl 5spd.



happy rotary'n /_\!