eroy87

The car will bog down and stutter under load in gear only, at about 3-4k rpm. Change in throttle has some effect to this, if i am light on the throttle i can get it to smooth out, unless rpms are high enough.
I know it sounds weird, but this seems to change depending on outside temperature. on a very hot day, it can stutter as low as 2k. but today was a much cooler day (maybe 65°F) it would only bog down at 4k. which makes me wonder... could it be the injectors struggling at higher heat? or could it be the previous owner's hot air intake not getting enough air?



I recently replaced the clutch on my car, and I don't know if that caused it, but I had removed and replace the Speed and reference sensors, I gapped them, but was unable to put the bell housing back on with them in place, so I ended up unbolting the bracket holding them on, and hoped they were in place after. But it starts fine. so im not sure if incorrect gap for the sensors could cause this.

Another Idea is a clogged fuel filter, Which I only replaced very recently, but who knows, there could be crud in the tank that caused it.

Please let me know your thoughts and opinions on this.

bonus: picture of my car

Zirconocene

Pretty car, thanks for sharing.

Have you looked at Clark's Garage? That site has a lot of good info about these kinds of things.

Separate from that advice, that air filter looks pretty old and in need of refreshing. I'm partial to the OEM setup, but you may not be able to move back to that setup, depending on what you got with the car, so maybe just a new filter, or cleaning that up might help out a bit.

Good luck

walfreyydo

Sounds like fuel related and seems like you are on the right track.

Things I would check:
-Fuel pressure (this will tell you alot, if pressure too high, FPR issue, if too low, blockage - pump or filter/tank screen issue) Youll need a gauge and an M16x1.5 adapter in order to connect it to the fuel rail bung
-AFM, run through the tests on clarks, probably wouldnt hurt to reposition the arms regardless, definitely do so if theres a deadspot in the voltage reading (AFM measures incoming air, and causes the car to stutter when it hits that deadspot, usually at a consistent RPM or throttle position)
-Injectors clogged (less likely but if the above all checks out it wouldnt hurt to send them out to get cleaned).
-DME relay (also known as the fuel pump relay - usually when these go the car dies but jumpering it is easy and you can drive the car to see if the issue goes away when jumpered/bypassed - also on Clarks)

Sensor gap on the speed reference sensors could also be related, this is described on clarks how to properly gap.

Info here:
https://www.clarks-garage.com/shop-manual/ts-01.htm

T&T Racing

First step, I would do the fuel rail pressure test per Clark's Garage.

eroy87

okay, so its gotten a lot worse recently, the stuttering shows up at low rpms as well as giving it more than 5% throttle. i drove it today, i couldn't make it up a steep hill, it just bogged down, i had to coast backwards to where i could turn around. when i went up a slightly less steep hill, it stuttered all the way up while in first gear like it was jumping. It also cuts out completely in neutral at about 4k rpm if i floor it, then it backfires if i hold it open too long. I wasn't able to pressure test, the set i tried at work didn't have the right adapter. i did replace the fuel filter and air filter. neither did anything. I did test the AFM and while i opened it up to check voltage, It reads OL at about half way open. also another thing i noticed is when i come to a stop sign, the fuel pump will just stop for about a second or 2. sometimes affecting starting off in first gear making it very jerky.
so im thinking, fuel pump could be bad, even though i replaced a few months ago when i first got it. it had been sitting for about 2 years, this could've led to bad gas gunking up the pump? I did cut open the old fuel filter. it looked clean. another possibility it the injectors.
please let me know what you think about this.

T&T Racing

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Before you buy another replacement part, do the fuel pressure tests per Clark's Garage. Fuel rail pressure must be in spec otherwise the fuel/air ratio is either too rich or too lean if all other components are functioning within spec.

walfreyydo

Sounds like you tested the AFM and it failed... Clarks garage has a guide on repositioning the arms, I would recommend doing that.

Also, test your fuel pressure. Youll need an adapter, I think the rail is a M16x1.5 (but dont quote me on that) and your pressure gauge is likely 3/8" so youll need to get an adapter.

eroy87

So I got a new fuel pump in the mail, because it didn't quite sound right, it was loud, and cut out pretty frequently. Turns out, the fuel hose that goes from the tank to the pump was kinked really bad and restricted fuel flow to the pump, hence burning up the motor and killing it. So it was a really simple issue that i didn't even think about.

boom10ful

Nice find! Was it an aftermarket or OEM hose?

eroy87

I have no Idea as i haven't replaced the hose before, a previous owner could've put that there. not sure what a OEM hose would look like. but to solve the issue, i just ran out to a local hardware store and bought a 90° elbow that fit then hose clamped it on, and boom, no more stutter.

Gage

I recommend installing the correct hose 95135655700 before the hardware store elbow disintegrates from ethanol fuel and destroys another fuel pump.
Also a good idea to source the correct clamps (not from a washing machine) and a proper hose clamping tool or at least smooth jaw locking pliers.

T&T Racing

Bump. What was the outcome?