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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
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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.
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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
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lol (bangs head)
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Originally Posted by certifiednut
(Post 8156872)
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.
Originally Posted by w0ppe
(Post 8156998)
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 |
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
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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.
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Originally Posted by wmelon137
(Post 9117356)
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.
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Make sure your auxiliary ports are opening too.
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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
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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
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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.
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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.
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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?
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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.
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Originally Posted by w0ppe
(Post 8156998)
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 '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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Originally Posted by BOFHMike
(Post 9787131)
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.
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. |
Originally Posted by HAILERS
(Post 9787281)
Or driver the car using little pedal until you reach 5000rpm. Should. Then stomp the pedal at 5000 and see what happens.
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?? |
Originally Posted by suck_my_rotor
(Post 9795224)
quote fail...:scratch:
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Originally Posted by HAILERS
(Post 9787281)
Or driver the car using little pedal until you reach 5000rpm.
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 /_\! |
If it seems like you're hitting a wall, check the ECU Ground on the Rear rotor housing. Search for Rear Rotor housing ground.
I had a car do this, and I checked the ground when I had the manifold off. Either way it loosened up. This was on my 88' GTU. I ran through everythign because i felt positive it wasn't that ground. Turns out it was, I was able to take the solenoid and UIM mount off of the drivers side and clean the ground up & resolder it. Put it back on, Absolutely no problem anymore. |
Originally Posted by Molotovman
(Post 9821996)
If it seems like you're hitting a wall, check the ECU Ground on the Rear rotor housing. Search for Rear Rotor housing ground.
I had a car do this, and I checked the ground when I had the manifold off. I'll pay for the 12 pack if anyone in the area wants to help me out over a weekend. :) |
Originally Posted by BOFHMike
(Post 9823967)
Looks like I need to take the UIM off one way or the other. Might as well pull the LIM, replace the injectors, and clean the Aux port rods while I'm in there.
I'll pay for the 12 pack if anyone in the area wants to help me out over a weekend. :) |
my car did this same thing, but now it will only start and run for about 5 seconds then cut off.
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Originally Posted by itsmeboosted
(Post 9826466)
my car did this same thing, but now it will only start and run for about 5 seconds then cut off.
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its an S4, and it's not throwing any codes.
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Originally Posted by itsmeboosted
(Post 9826939)
its an S4, and it's not throwing any codes.
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'86 gxl. Non turbo, 126,000 5speed. anything else???
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Originally Posted by Molotovman
(Post 9824440)
To do the ground on an S4 you don't have to pull the UIM if you have a couple universal joints handy. Just take out the solenoid and the mount on the drivers side and it gives you some room to squeeze in there.
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Originally Posted by HAILERS
(Post 9787281)
************************************************** *******************************
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. I just tried all of the above and all check out. I get 12v on 1 wire on each secondary. I can get it to creap by 3800 with just a hair throttle but if i give it more gas at any time over 3800 it starts doing the "rev limiter" thing again and drops to 3800. Pin 2b, does indeed have 3.5 volts on it. Ground on the rear rotor housing was cleaned when i put the motor together a few days ago, made special note of that due to issues i had with my old car. I am lost at this point, no clue what to try next. The engine runs perfect below 3800. |
I also know that the ECU is not trying to fire the secondary injectors for some reason, voltage at injectors stays the same even when revving it.
Could it be the ECU? I did just buy this ECU from ebay since i could not find one locally in DFW. |
Originally Posted by Texas_Ace
(Post 9867186)
I also know that the ECU is not trying to fire the secondary injectors for some reason, voltage at injectors stays the same even when revving it.
Could it be the ECU? I did just buy this ECU from ebay since i could not find one locally in DFW. Just because the ground is secure at the engine does not necessarily mean the grounds are not an issue. Regrounding near the ECU will not hinder anything and might actually help. There are four to choose from. Pin 3A,3G,2R and 2C. The injectors require a ground signal from the ECU to pulse properly. You could check for pulsing of the secondaries but you need the rpms to reach a certain level to check the pulsing. If you take an led light and place the red wire of the led into pin 3I and the yellow into pin 3H - light green/ white wire (front secondary) with the engine running try to reach an rpm that will trigger the secondaries and if so you will see the light flash. Remove the yellow wire from 3H and move to 3F -light green/red wire (rear secondary) and you should see the light flash under the same conditions. |
Originally Posted by Texas_Ace
(Post 9867186)
I also know that the ECU is not trying to fire the secondary injectors for some reason, voltage at injectors stays the same even when revving it.
Could it be the ECU? I did just buy this ECU from ebay since i could not find one locally in DFW. |
Originally Posted by satch
(Post 9867259)
This is for an S4. Same applies for an S5 except the name and location of the pins have been changed to protect the innocent.
Just because the ground is secure at the engine does not necessarily mean the grounds are not an issue. Regrounding near the ECU will not hinder anything and might actually help. There are four to choose from. Pin 3A,3G,2R and 2C. The injectors require a ground signal from the ECU to pulse properly. You could check for pulsing of the secondaries but you need the rpms to reach a certain level to check the pulsing. If you take an led light and place the red wire of the led into pin 3I and the yellow into pin 3H - light green/ white wire (front secondary) with the engine running try to reach an rpm that will trigger the secondaries and if so you will see the light flash. Remove the yellow wire from 3H and move to 3F -light green/red wire (rear secondary) and you should see the light flash under the same conditions. So those pins you mentioned above, does it matter which one i use? just run 1 of those to ground or all of them? I am thinking it might be the ECU, it is pretty beat up and i picked it up off ebay. I checked the secondaries with amultimeter, not perfect but there was never even a hint at them trying to open. and thats also what it acts like. I will try adding some grounds, what pins/best places are there to add them? Anyone in the DFW area have a spare ECU i could try?
Originally Posted by ItsFun
(Post 9867267)
My car did the same. Open up the ecu and check for a burnt up board. Also secondaries wont open when the car is not under load unless you fool it. To trick it warm up the car, unplug the boost sensor vacuum and tps then rev it up at 3800rpm, what do you see? From what I understand from you explanation seems like secondary injectors are not even trying to open. like mine. Which had a shot ecu... shot from a shotty wires under the hood.
I will pull it apart later tonight and see what it looks like. |
you can run one ground close to the computer. general area, as long as its a ground, like one of the computer mount bolts I believe? check it first I dont recall. HAILERS has something better written up but you`ll have to search it, I have no idea where I remember seeing it.
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Originally Posted by ItsFun
(Post 9867349)
you can run one ground close to the computer. general area, as long as its a ground, like one of the computer mount bolts I believe? check it first I dont recall. HAILERS has something better written up but you`ll have to search it, I have no idea where I remember seeing it.
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Originally Posted by Texas_Ace
(Post 9867592)
Yeah, i am not real worried about where to run the ground TO, i am more worried about where to run it FROM. any of those pins listed will work fine? any better then others? more then 1?
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Ok, i will try grounding one of those and see what happens.
BTW, never seen a pin out like that, usually the letter is the connector and the number is the pin but this looks backwards. 3A would be the first pin on the biggest connector? |
Originally Posted by Texas_Ace
(Post 9867632)
Ok, i will try grounding one of those and see what happens.
BTW, never seen a pin out like that, usually the letter is the connector and the number is the pin but this looks backwards. 3A would be the first pin on the biggest connector? |
Originally Posted by satch
(Post 9867647)
Are we talking S4 or not? If so, the the number refers to the plug and the letter refers to the position. In this case (S4) 3A is the smallest plug upper most right looking at the plug from the back (or wire side).
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Originally Posted by Texas_Ace
(Post 9867686)
Yes, it is an S4, then i guess i will use that pin since i know where it is lol.
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True, although i am thinking more and more it is the ECU and not the wiring, the PO said the car ran great before the motor blew, so i see no reason for the wiring to have just gone bad all of the sudden. On the other hand i have an ebay ECU on my hands, that i think is a lot more likly.
As you say still a good idea to do the grounds though. |
Originally Posted by Texas_Ace
(Post 9867686)
Yes, it is an S4, then i guess i will use that pin since i know where it is lol.
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Originally Posted by Texas_Ace
(Post 9867632)
Ok, i will try grounding one of those and see what happens.
BTW, never seen a pin out like that, usually the letter is the connector and the number is the pin but this looks backwards. 3A would be the first pin on the biggest connector? |
Originally Posted by ItsFun
(Post 9868333)
Fuel and emissions section of the FSM has a very nice pin identification layout.
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