why cant i go past 4k RPM????
 

car spec:
87 rx7 N/A
new oil
new plugs
new fuel pump and filter
new ING wires

for some reason when i drive my car it feels like i hit a hardcore rev limiter crazy hesitation and jerking at 4k RPM!! what may cause this?!

did it happen randomly or have you done something right before it started?

Can you free rev the car in neutral past this supposed wall? When driving can you slowly pass the 4000 rpm level?

i changed my trailing coil and leading coil cuz my car was all eff'ed up.

it will go past it slowly sometimes but when i try to give it more gas it jerks violently.

plug in your secondary injectors.

lol they are plugged :nod:

check them again.

There are two wires for each injector plug. If either wire is pulled back within the plug then that injector won't work. Can you rev the car while idling to a rather high rpm?

i cant. it kinda sounds like a throttle bounce. peaks at 4k then drops a few hundred and then bounces back up again and again and again :lol::scratch:

tps?

have you tried the search function.. its as easy as searching for 3800 rpm hesitation,, 15 billion threads on it .. its usually a fault in the loom crimps .. and the faulty crimps are about 25 cm up the loom from the ecu

If you cannot rev the car while idling in neutral past 4000 rpm then you can check your fuel pressure and you might want to remove the O2 sensor (unscrew it from its housing) so as to check and see if things change for the better.

not likely crimps if it is a california car, unless it came from an eastern state and driven through winters.

pull the secondary injector clips off and inspect the pins, tug the wires a little bit and see if any are pulling out. takes less than 5 minutes. if the engine was ever worked on MOST ALL of the time i see that people just yank off the connectors because they can't figure out the simple wire locking mechanism that holds them in place.

could be a plugged up cat like Satch is indicating but it wouldn't be a quick transition and the car would likely rev freely all the way to redline until put under a load.

the TPS wouldn't be faulty at a set RPM, it would be faulty at a certain throttle position.

fuel pressure would be the second place i would look outside the secondary injector clips. a plugged up fuel filter or dying pump will still allow the engine to run but it will start to run out of fuel when you load the engine up, especially when the injectors are transitioning at 3850 RPMs.

lol here is a video to better explain what is going on. thanks bud

tps calibration/swap ..do this first

..uh guys...
https://www.rx7club.com/2nd-generati...-help-1009284/
OP has had electrical problems before.If anyone cares to check his other threads out,it may help get this problem ironed out!

Thank you.

Its your secondary injectors, they either need to be replaces or the connections need to be cleaned, there is something called the "ground of death" which happened to me, you gotta pull the intake to get to it buts its worth it, unless you wanna rev half of what you could for the rest of your cars life

Do you have a link to that thread? Thank you again

ya know, someone put the linkon my thread a couple months back and it reeally helped me out ill look for it

scope that:

https://www.rx7club.com/2nd-generati...tering-998575/

and make sure the electrical connections that plug directly into your injectors are good, one of my metal pieces came out so now its connected with a peice of paper clip, ghetto mechanics haha

I agree. I had the same problem (different than the 3800 hesitation, feels more like a fuel cutoff) I was looking for fuel problems and tried many things before I calibrated the TPS. That fixed the problem.

Of course it could be any part of that circuit that's the problem... connections, the ecu, bad adjustment, or a bad TPS altogether. Make yourself a test light with about $10 in radioshack LEDs and terminals and hook up per the FSM. (There is a how to on here somewhere for it).

Once I adjusted it correctly... the problem disappeared. On another RX-7 the TPS would not calibrate to make the lights do what they should. I replaced this one and adjusted the new one in... again, problem gone.

Replace omp,ecu,tps at the same time.

replace the car while you're at it.

That's not very nice. Any car can be fixed with patience, knowledge, and effort. The usual issue is money.

Your trailing injectors might be wired backwards....check them.

I'm sure his response was based on the post before his, which mentioned replacing a number of items.

yes, it was laced with a bit of sarcasm. like everyone has access to plentiful used parts, if someone went out and bought all new parts that list would equal several thousand dollars and still likely wouldn't fix the issue.

i still am sticking to my guns, check the secondary injector clips, takes a few minutes and i'm wondering why it hasn't been done already. sometimes it feels like i'm pulling teeth.. it doesn't cost a dime. a TPS issue would cause other symptoms along with the brick wall at 4k. a loose secondary injector clip usually results in both secondary injectors not firing which causes the severe lean condition that usually causes this. grounding issues usually result in a severe stutter at 4k but power is regained after the injectors have fully staged where the clip issue feels like a severely clogged cat, engine struggling to get beyond 6k.

Some stuff can take seconds for an experienced mechanic to fix that could take an infinite amount of time for someone inexperienced.

Knowledge is power.

thank you so much for the info and for taking the time to help share info

update.

replaced the following:
-engine main relay
-circuit opening realy
-new TPS and adjusted
- all ignition coils
-ignition switch

ive checked the MAF and followed the check procedures via FSM and it check out okay.
car starts and dies right after. i see RPM needle bump when i starts %100 of the time
but when its cranking and it doesnt start i dont see no needle bump. ive checked the injector clips and they are okay.

im running out of ideas on how to fix this problem hmmmm any suggestions

i checked some of the pin at the ECU with the key position ON and this is what i found. FSM 4A CONTROL UNIT PAGE 4A-31

1M-.93V
1N-5.33V
1P-5.34V
1Q-5.35V
1T-5.35V
1U-8.36V
1V-.01V
1X-0

2B-8.19V
2C-0V BUT RESISTANCE 2.90
2D-4.14V
2E-8.63V
2F-7.89V
2G-5.20V
2H-8.20V
2I-6.14V
2J-6.14V
2L-8.16V
2R-0V RESISTANCE GOOD

3A-0V RESISTANCE GOOD
3B-1.63V
3C-11.55V
3D-1.62V
3E-11.45V
3F-11.45V
3G-0V RESISTANCE GOOD
3H-11.44V
3I-11.44V
3J- NEGATIVE 0.12V? HAHAHA I DONT KNOW

some volts are higher than what its suppose to be in the FSM

Help?! Plz

Help?! Plz

if it now is starting and stalling then you may have created a vacuum leak during your tests. jumper the yellow fuel pump test connector and see if it starts and runs without stalling.

the AFM has an internal switch for the fuel pump, when the door closes enough it shuts the fuel pump off, vacuum leaks bypass the AFM so the door will not open as much as it should and in some cases close enough to shut the engine down and the AFM will test out ok.

if the engine runs with the jumper, keep it idling manually if necessary and use a can of carb cleaner to spray around the engine to check for vacuum leaks. the idle should stabilize or stumble when you come across an area with a leak.

Pin 2C grounds 7 sensors and you gave the voltage readings for 6 of these sensors and they are all wonky and exceed the proper values by a large degree.. You might want to disconnect the AFM and take another round of readings at the following pins. 2B, 2L, 2I, 2H, 2F, 2G. If you get the same readings then add an additional ground to 2C and ground it to one of the ECU mounting bolts.

To answer your other thread question (which is related to this thread)...

Voltage on 3J is supplied from the battery according to page 50-29 of the FSM (Which is easy to find on the FAQ in this section).

Hope this helps.

i dont know what the last owner did but i can hear my fuel pump just in on position.

i dont know what i did but i was messing with some around the maf and i tried to crank it. out of sheer luck it started. held idle. when it got warm enough i brought the revs up to 5 and 6 thousand and it didnt hessitate or hit a brick wall. bit its smoking a bit.

what should i look for since the car starts and holds idle? anything you want me to look at in particular? but i will add a extra ground to that pin tho

ooh and thanks again and sorry

well i was reading the wiring diagram and i was following where it goes and it hits FEM-02 then splits off to 9 directions from what i can understand. i dont know what those 9 are. thank you

The "9" don't matter. Look for the bl/W wire on the FEM-02 plug. I believe it hooks up with a Bl/R wire. Check to see if you have voltage on either of these.

Are you sure you were able to get an accuracte reading off of 3J? If I remember correctly, the wire is slightly larger diameter and tough to get a DMM probe in with it.

Just a thought.

Good Luck!

Rob R.

Did the OP ever check to make sure his trailing coils were going to the correct plugs?

thanks guys. i fixed the problem and i was on top of the engine. the ground was corroded and some wires were damaged. the car runs and feels great. thanks again guys

post 10 told you it was the earth issue .. and you ignored it till it was rammed repeatedly...yet every single search on hestitation would have listed it as number 1 cause

... you have fixed it on top of the engine..

but you WILL find its not the full fix ..

as many people have found already,, the real issue lies in the conductivity through the brass crimp just up from the ECU plug that is where all those earths bundle for 2C

many people go through the earth adding to top of engine or to the pressure sensor ( as original early s4 engine looms lacked one )
and still find they are back resoldering the crimp and adding the new earth loop to the case

okay if you look at all other my post hesitation wasnt my only issue i had many problems. read through all my post before making further statements thanks.

Had the same problem as you described. Pulled my hair out chasing it. Tried everything. Fixed it today and rotary eve mentioned it early in this thread. Check the secondary injector fuel injector clip. To test this I disconnected the fuel injector wire to the injector that closest to the firewall it ran poorly as you described. Resided a new clip and it now runs like a champ. I've been chasing this for 3 months!

What does the OMP have anything to do with OP's issues. If anything, he should delete the OMP, install blockoff plate, remove and plug the injectors and clean the ECU ground while at it.