1990 240sx ka24e (sohc) hard to start slow acceleration

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dccse3k
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My car will not start when it is cold or warm unless i depress the gas pedal. After that it idles perfect. In neutral when i rev it the engine seems to have power and doesn't misfire at all sounds completely normal. When i go to drive it the car seems like it is starting in 2nd or 3rd even though i know i am in first and the acceleration is nowhere near what it should be.

I've tried cleaning the maf with maf cleaner, spraying around w/ carb cleaner for vacuum leaks found none, unplugging and messing around w/ vacuum lines, the timing is right on checked w/ timing light.

The computer gives me code 55 which means normal in mode 3 and in mode 2 it is constantly in open loop mode and never in closed loop mode so i suspect something do with fuel but i am not sure what.

What could be the problem, fuel pressure? but why would it sound so good in neutral and it eventually gets up to speed just slowly, does the tps affect the amount of gas the injectors squirt maybe they arent squirting enough. The spark plugs look a little lean but nothing too bad.

anything else i should check? thanks.


indomiekid1
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im thinking fuel pressure but you are right, doesn't make sense.
injectors?

Klits562
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i had the same problem but mine was an automatic is yours manual or auto?

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dccse3k
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its still an auto what did you do to fix it?

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sx moneypit
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You might want to check your catalytic converter.

Klits562
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dccse3k wrote:its still an auto what did you do to fix it?
i reset my ecu
mine felt like it was stuck in 2 or 3 it had no power in drive at low speeds untill i hit about 35 mph then it felt fine, i would put the trans in d1 or d2 and it would not downshift and it felt no different. I kept my battery unplugged for about 5 minutes then started her back up and she was fine.

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dccse3k
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ah yeah it shifts fine from d1 and d2 so i know im in first and i have tried 2 ecu's already. Im just gonna start driving it (had been sitting broken for a year and a half) and maybe some s*** will clear up or it will get worse so i can get a better idea. Its not too bad for a daily driver but something is definitely wrong.


if my only problem was that it wouldnt start cold unless i depressed the accelerator what would be your first guess as what was wrong?

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sx moneypit
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Have you checked you TPS?

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comatoseculture
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Car: 1990 240SX coupe. Currently running on Megasquirt.

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also have you checked the coolant temp sensor for the ecm?

First guess to cold start only with gas is...honestly not enough info. too many possibilities. there are only so many sensors needed to go into closed loop so, shouldn't that be the first route of investigation?

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dccse3k
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My spark plugs look like it is running lean. Is there any quick mechanical way i can make it run richer like unplugging something that anyone knows about?

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comatoseculture
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Car: 1990 240SX coupe. Currently running on Megasquirt.

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no. Can you t in a fuel pressure gauge/pay a mechanic to do so?

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dccse3k
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Ok so i suspected fuel pressure and came across a cheap fpr and that changed nothing still hard to start and no power when the rpms are low like below 3500 accelleration is very slow.

I took out the fuel pump to look at it and the sock was dirty as hell and i heard walbros in stock would smooth out acceleration so albeit not the best decision i felt it couldnt hurt so i put one in and there was only a slight change. Now after it warms put it will start without touching the throttle after about 3 seconds of cranking. The acceleration feels good after i get up to 3500 rpms (auto) and maybe i am just remembering wrong how quick the accelleration of the car is? i have been driving my motorcycle for the past year and a half due to my camshaft snapping and have finally got this car running.

reguardless it still doesnt start cold unless i press the throttle down. What other problems could it be? I have ran fuel injector cleaner through it and taken off the injectors and tested them and they seemed to be ok. ohm readings are good. I tested the tps and it checked out ok. compression was pretty low about 155 across but it was uniform and oil didnt help much if at all.

What else should i check?

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dccse3k
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So i think i may have a vacuum leak around the fuel injectors where the join the intake manifold. The cause of this seems to be my bushings and i just went to the junkyard and got some more.

The problem is that they have these little plastic caps that make the o ring seal fit tight on the tip of the fuel injector which i have only 1 that is still on the injector. has anyone else had any trouble with these plastic caps?


EDIT: So i called the dealer they said they have them and i go to get them. Turns out he though i was talking about the o-ring not the plastic cap and they don't sell the cap. Does anyone have any idea where I could get some? i have searched online but couldnt find any, or can someone confirm that you dont need the plastic caps?

on the bright side i mentioned the lifetime seatbelt warranty and the service rep helped me out w/ no trouble and im bringing my car in for fixed seatbelts!

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sx moneypit
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I have gotten the caps before in some kind of rebuild kits for injectors.They came with the o-rings,screens and caps,i don't remember where i got them though.I have put injectors in without the caps and did not have any problems.


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