KA24E (sohc) acceleration issues

[umm_91]

ok so i sold my fastback and picked up a coupe a couple days ago,
changed oil, plugs, fuel filter, coolant, and got a new battery to make troubleshooting easier plus the car has been sitting.

car is a 1990 coupe SE ka24e (sohc)

heres the issue,
my car is hard to start and takes a couple tries to get it running, somtimes i have to depress the pedal to get it started.
when it starts up sometimes it might die out, and if it doesn't then it idles real rough.
no vacuum leaks and maf is clean.

when i rev up in neutral it revs fine but when in gear, it tends to hesitate alot.
i fixed the timing, and the coil, dizzy and cap, and wires are cherry.

help me please, there are a couple events coming up that i would like to participate in!
thanks in advance!

[Neon_rain519]

Its most likely fuel pump. I had similar problem stumbled under acceleration, rough idle felt under powered. Bought a new pump it was like night and day.

[DxZoo]

Check the injectors and injector o rings as well.

[truebluegallo]

fuel pump hose or the pump its self mine did the same shit

[DataXUnknown]

I have the same problem, my bet is on either the fuel pump or o2 sensor. So far I've: Adjusted the TPS correctly, did the timing, replaced the cap and rotor, checked all my injectors with multimeter and automotive stethoscope, cleaned MAF and throttle body, double checked all my vacuum lines, replaced spark plugs and wires, changed oil, changed radiator/water pump/belts (explosion happened), changed coolant

So yeah, the only two things left on my list pretty much is fuel filter, fuel pump, and o2 sensor. I'm thinking fuel pump.

[GunmetalSR]

while ur changing the fuel pump check to see how dirty the tank is and if its really dirty then pull it out and sea foam it

[umm_91]

thanks everyone! im gonna check on that, i had a similar problem before with my fastback but it only happened in mid-drift and it was the fuel pump strainer. not as massive as this though.

[xBtony]

Hmm my car is having the same problems. Lol, really helpful thread.

[voodoo_child]

damn my single cam is acting the same way. rough on idle, i replace the injectors with the fuel rail assembly and its still doing the same thing. im going to try the fuel pump and filter. keep this thread updated for any results.

[driftn_silvia]

Also, when engine is hesistant, is it near empty in fuel?

Had the same problem and symptom, the Fuel Pump was faulty. I eneded up changing the fuel pump and no longer have those symptoms. except when near empty the engine is hesitant.

[chiboy002]

my dual cam kinda has the same issue. under partial throttle, like from a stop sign or light, it kinda chokes before it fully picks up. I think its because of lack of back pressure since i have headers and a straight pipe. could be wrong though

[voodoo_child]

^^^check your vacuum hoses on the EGR system. i had that problem before.

[umm_91]

UPDATE: i took out the fuel pump,
checked the connectors and cleaned it,took out the strainer and cleaned it up a bit,
then to find that the fuel pump hose was cracking and a little cut, i replaced that hose, put the fuel pump assembly back together and dropped it in.
added some fuel system cleaner then
i put the key on the "on" position to hear the pump prime and it sounded stronger than before.
cranked the car and................
SAME SH*T. took a while to start and when it did, it felt the same.
i also noticed its harder to start at night and morning than to start in the afternoon.
IDK.
holy cow im running out of choices.
please help! thanks again for all the input!
still trying to find a remedy.

[voodoo_child]

your using the same pump right? could it be your crank position sensor?

[DataXUnknown]

Yeah I just changed my fuel pump out today. The rough acceleration is gone now, but my idle is still pretty damn shitty. Maybe it's because I have an automatic? It's like super misfiring when it's at idle.

[umm_91]

im still using an oe style pump.
and my idle is at 800 then will drop to 400-300 then back up, all in a matter of a split second!
it sucks really, cause i need to compete at the end of the month and my t2/3
hybrid is goin in soon but i want to make sure everything is fine before the turbo goes in.

[voodoo_child]

you sure you dont have any trouble codes?

to DataXunknown, mine is exactly doing the same i was thinking of raising the idle to 1000rpm. im running out of option with this idle problem. the whole car shakes when its on idle.

[umm_91]

UPDATE:
No trouble codes, reads all clear.:-/:cry:
i dont know what to do! ima try a new fuel pump and hope it works out.
any suggestions on an aftermarket fuel pump?
and the "cc" on the rx7 turbo injectors?
cuz that might be the injectors im going to use on the boosted application.

and if its ok to use an aftermarket pump on stock mods? i only got headers and intake right now.

help!

[DataXUnknown]

you sure you dont have any trouble codes?

to DataXunknown, mine is exactly doing the same i was thinking of raising the idle to 1000rpm. im running out of option with this idle problem. the whole car shakes when its on idle.

I tried raising the idle, mine is automatic so raising the idle just raised it in park. In drive it is still just about the same. If your idle is not around 800, I would suggest checking the TPS with a multimeter. It should be around .45 or .50 if I remember right. If it if fighting to stay up there, well, today I just changed my fuel filter, air filter, and o2 sensor. That seemed to help a shit load (besides changing the fuel pump as well earlier last week). I'd say o2 sensor, and if your's is an automatic, the TCC solenoid is probably going out (basically torque converter is taking a dump). If it takes a long time from park to drive, then most likely you need to convert or replace some parts on the tranny.

Other than that, all I can suggest is vacuum leaks.

UPDATE:
No trouble codes, reads all clear.:-/:cry:
i dont know what to do! ima try a new fuel pump and hope it works out.
any suggestions on an aftermarket fuel pump?
and the "cc" on the rx7 turbo injectors?
cuz that might be the injectors im going to use on the boosted application.

and if its ok to use an aftermarket pump on stock mods? i only got headers and intake right now.

help!

I believe the stock RX7 injectors were 360CC's? As for the fuel pump, if you're planning on boosting it, that definitly isn't a "stock mod". What is a "stock mod" anyway? You can't mod a car and have it be stock at the same time unless it's factory modding you are doing I suppose you can consider that. I would get the stock fuel pump btw, they are $85.99 (plus tax) at autozone. Don't forget to get the strainer as well, they don't come with it, an extra $20 I believe.

[LOUD240]

ok , check the black box above what i believe is the EGR just forward of the brake fluid resevoir has a hose going over to the air box, check it for holes that the exhaust system has melted into it, mine had some holes I replaced the box with a new one from nissan . My idle is now very smooth

The lugging under acceleration is generally a vacuum leak.buy 10 ft of vacuum line and go to town

[voodoo_child]

i dont have any problem in acceleration excepts it jumps only into 2nd gear which i think is the mounts, and yes mine is A/T. just problem with the idle but its around 800rpm. my co-worker is a smog tech he check the system using the smog machine and somehow im running rich only on idle. could be the o2 sensor is faulty? so far what ive done is replacing the fuel injectors together with the fuel rail assembly check the wirings, and check for any vacuum leaks.

[umm_91]

I tried raising the idle, mine is automatic so raising the idle just raised it in park. In drive it is still just about the same. If your idle is not around 800, I would suggest checking the TPS with a multimeter. It should be around .45 or .50 if I remember right. If it if fighting to stay up there, well, today I just changed my fuel filter, air filter, and o2 sensor. That seemed to help a shit load (besides changing the fuel pump as well earlier last week). I'd say o2 sensor, and if your's is an automatic, the TCC solenoid is probably going out (basically torque converter is taking a dump). If it takes a long time from park to drive, then most likely you need to convert or replace some parts on the tranny.

Other than that, all I can suggest is vacuum leaks.



I believe the stock RX7 injectors were 360CC's? As for the fuel pump, if you're planning on boosting it, that definitly isn't a "stock mod". What is a "stock mod" anyway? You can't mod a car and have it be stock at the same time unless it's factory modding you are doing I suppose you can consider that. I would get the stock fuel pump btw, they are $85.99 (plus tax) at autozone. Don't forget to get the strainer as well, they don't come with it, an extra $20 I believe.

i mean on basic mods. will a stronger fuel pump make me more rich in fuel?
because i dont want to get a oe style pump then have to change out and buy a stronger one when the boost goes in.

[umm_91]

UPDATE:
replaced the fuel pump and strainer and still the same,
tired of wasting money on one problem.

i also noticed the MAF has a crack on the plastic
(air leak maybe???)
i dont know if that helps. getting a maf later so we'll see how that goes.

any other suggestions? i know there are people out there with the same problem looking forward to this thread for a remedy.
thanks

[thefro526]

I'm having similar issues.

When coming to a stop sometimes the car's idle will surge between 200rpm and 800rpm.

In First and Second Gear the car feels very sluggish, but will rev over 5k rpm.

In Third and Fourth Gear the cars still feels very sluggish, but won't rev over 4.5k and 5k respectively. When it hits those Rpms the motor just stops, it's not like a rev limiter. Any ideas?

[umm_91]

UPDATE: still same problem, re-did the timing once again checking the cam to crank positions out it all back to find that its still the same, got me a free new cap and rotor, gonna try right now.

[voodoo_child]

i think this issue on rough idle is more likely on A/T?

[umm_91]

UPDATE: i put on the cap and rotor, and still the same,
read the ECU.....AGAIN and it reads Intake Air Temp Sensor (41)
im running out of things to think of.
gonna compression test soon.

[DataXUnknown]

One thing I've read about on other cars, is the TCC solenoid (only on A/T). Basically our automatic trannys may just be taking a shit. I couldn't figure out where the TCC solenoid is on our trannys, or if we even have one, but besides that the only thing I could ever see possible is vacuum leaks.

[saleaf]

i read you have a clean MAF. but i had a clean one two. and i said F it bought a new one(brand new) just to see.... and night and day. went from stalling shit idle to perfect. try that. also if you dont have an air intake temp sensor it will run like shit. i just got my 240 and im doing all the same work you are. like i said for me the MAF did the trick. i also replaced my EGR valve and the EGR sensor. if your EGR valve is all filthy inside and has been on the car since 1990. get a new one. should help smooth things out. when i removed my EGR sensor it had about 1/4in of nastiness caked on. so try cleaning that too. or replacing it.

[saleaf]

also might wanna check the vacuum line off the intake box. make sure its there. haha. mine was missing. replaced it, ran a little better.

[umm_91]

egr dont matter. i took everything off, and im pretty sure you dont need a damn intake air temp sensor. i live in guam and dont care about emissions.

UPDATE:
alternator recently gave out. maybe early signs of faulty? due to low voltage? getting an alternator soon.

[Zero-Offset]

Air intake sensor shouldn't matter. Mine is disconnected, and always throws a code, but it runs fine, with my cone filter.
I had a similar problem before, shitty/hard to start, and would stall lots at random points. The 3 things i replaced that helped a lot were another KNOWN working MAF, new fuel pump relay (thought it was the main cause, its a fairly big relay in the fuse box, less than 20 bucks, good thing to try) and LOW as shit on gas.
Since our cars are old, the fuel level sender can read off somtimes, so i found adding some gas if you know its low, helped a bunch.

Hope you can figure it out, i was frustrated as shit, and was almost ready to swap the whole engine out lol. GL!

[s13 @ fullboost]

check and clean IACV wouldn't hurt

[umm_91]

Air intake sensor shouldn't matter. Mine is disconnected, and always throws a code, but it runs fine, with my cone filter.
I had a similar problem before, shitty/hard to start, and would stall lots at random points. The 3 things i replaced that helped a lot were another KNOWN working MAF, new fuel pump relay (thought it was the main cause, its a fairly big relay in the fuse box, less than 20 bucks, good thing to try) and LOW as shit on gas.
Since our cars are old, the fuel level sender can read off somtimes, so i found adding some gas if you know its low, helped a bunch.

Hope you can figure it out, i was frustrated as shit, and was almost ready to swap the whole engine out lol. GL!
thanks! i will try that after the alternator, just lost my job so it will be a while before i update.

check and clean IACV wouldn't hurt
already did, didnt help, thanks though.

[bb4_96]

i know this issue well. you didint swap an ls yet did you?

[umm_91]

i know this issue well. you didint swap an ls yet did you?
LS? what do you mean?

[Fatboi240]

most likely an injector problem

[voodoo_child]

^^^nah i replace my fuel rail and injectors and still has a shitty idle. i even check my wirings from the iinjectors.

[umm_91]

UPDATE: ok, turns out it was my alternator all along. all electrical components were not getting complete voltage.
reason why i didnt know was because i went through 2 new batteries and pulled the gauge cluster out to find that the previous owner took out the bulb for the battery!
oh well, at least i got some brand new shizznit that i dont have to worry about later.
thanks zilvia for all the help.