iv got an 87 na. before 4k it accelerates normally but when i hit 4k it stops goin and thats if i give it 100% throttle. when i give it less than half it keeps goin and doesnt die down. i was thinking it was my tps since i had it unplugged because it didnt work.. but i just got a new one today and it didnt really make a difference. anyone know what the problm cud be?

 

hesitation 3800rpm


read the FSM

 

wrong. fix your 5/6 ports, there not opening.

 

the VDI actuators don`t work...????


or what........................

 

Read the FAQ!

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

 

Its not the hestitation. If it was even at WOT he would still climb. He says that if he is 100% throttle then it stops going at 4000rpms. If have throttle it keeps climbing. That means the 5/6th ports aren't opening and its flooding out at WOT when the secondary's kick in. The exact same thing happen to me when I first got my car.

 

Its an 87. No vdi.

 

ya i was thinking it was the 5/6th ports.. thanks for the help..
and i did read the faq

how do u wire the 5/6 ports to stay open all the time.. im gunna search this rite now but i though id ask anyway

 

well first since you have an S4 NA this WILL WORK
i have an S4 NA and THIS DID WORK

start engine, put finger on throttle and push make sure both 5 and 6th ports open freely.. i freed up one a little bit by removing it and cleaning it with degreaser and banging it on ground until it worked.. but that didn't last long i have the hesitation again...



the caps above are because people will say it doesn't work unless under load.. gotta do this and that and blah blah blah STFU it works... LOL

 

and i dunno how you drove w/o tps plugged in, my plug just came loose and my idle started surging and the throttle was unresponsive. and forget gears put it in gear and it would buck... dunno unlucky me...

 

it drove better with the tps unplugged.. rite now it feels like it bucks more then before. without the tps the idle was really steady but sometimes in the morning it would idle around 2500 for a while then drop down..
but ya kool **** ill clean my ports tomorrow those are the ones rite above the header right?

 

I'm banking on a problem with the secondary fuel injectors.

 

Probably 3800 rpm hesitation, which comes from the secondary fuel injectors failing to engage at this rpm. See FAQ. Even if you glued your 5th and 6th ports shut you would have no problems. They are just there to add power and cannot possibly hurt a thing.

 

if its bucking check the connections on the plugs where the TPS plugs into harness check all 3 of those and make sure they are clean, no corrosion on the contacts.. mine did that same thing it would start surging the idle and i had to tweak the throttle at lights, then when i started moving it would go through 2nd gear then start bucking really bad and would barely keep moving
and the 5/6 ports are right above the header a rod coming out the top rear one is tilted to rear and front one is tilted to front kinda behind air pump if you have one.. if you want to take them off then you remove the two 10mm bolts, i had to pry mine off but you may not, they will pull straight off w/out disconnecting the rod (it will slide right off the other part) you will see what im talking about when you get in there...

 

i checked my ports and their working fine.. im starting to think its the injectors. should i just go get them cleaned out and tested or is there something else i should do?

 

I have the same issue right now and am going to swap mine for secondary injectors i know that work. I'll get back to you tomorrow.

 

did you adjust your tps when you put it on?

 

I'm experiencing the the same or similar problem.

Throttle @ ~30-40% acceleration is smooth to redline; throttle 50-75% there is intermittent surging/hesitation staring at ~3800-4000; the closer to WOT the more the hesitation occurs.

What I've tried:
- replaced old, clogged exhaust
- had ground wires cleaned/replaced (I requested this be done as per Aaron Cake's guide, but I can't say I'm confident about the work the shop did)
-5th 6th ports tested ok

- Original TPS tested bad. I bought one from a forum member and it tested ok. I adjusted it with a ddm, however, I cannot confirm the setting with the light method. It is either both lights or none. Adjusting the TPS with the ddm puts the lights close to the all one/ all off setting. When I unplug the TPS it drives pretty much the same except for a bouncy idle and some quirks.

TPS electrical issue?

Secondary injectors, recheck grounds, or something else? Is not being able to adjust TPS via lamp method significant....

 

no i didnt.. i dont know how.
i read that write up on how to do it but isnt that only for a t2??

if u can give me a link where it explains it better that wud be nice

 

http://howto.globalvicinity.com/gv_w...i=58&co=1&vi=1

http://fc3spro.com/TECH/HOWTO/TPS/tps.html

FSM manual 4A-50
http://www.cochran-racing.com/FSM/s4/index.html

 

the turboII s4 tps should be very similiar, yours is just easier to get to than a turboII.

 

ive heard its a poor ground on the ecu...

 

Have you done this yet?

 

secondary injectors kick in about 3400 rpm's dont they...
so this might be a source of the problem...
hmmm

 

The cause of mine was a faulty "variable resistor pack" never activating the secondary injectors. 99% of people fail to identify that as a possible cause. everyone I turned to fed me the wrong answers, even respectable people. I stumbled upon that solution unintentionally, I didn't even know what the damn thing was at the time. I'm not saying this is your solution, but look into it.

It has nothing to do with the 5th and 6th ports.. that's rubbish. They can be closed and the car will function seemingly properly.

fyi it's 3800 not 3400 (the guy above this post) easily mistaken for 4000 rpm none the less.