dreadhead89

I have a 90 ef si that i just did a d15b swap to. Now since ive done the swap the when I got to start the car and it is cold it wants to die and bog out, but after a few mins of running everything is fine and it starts right up,( as appose to it cranking over for a few seconds before starting cold). when its really cold it run rough then i give it gas it takes it a second then gose up then falls and usually dies. then when i restart it it usually starts up fine, or it repeats the process until it starts. Then its fine. I know its not the relay. Its almost like it dosent have fuel pressure for a sec!? Any ideas welcome thanks.

HaulingAddison

First thing I would do is check the codes on the ECU, but what I'm thinking it's probably the coolant temp sensor on the head of the car underneath the distributor. It's the 2 wire sensor. If that sensor get's messed up, it would run your car really rich when it was cold and cause your car to run rich, which in turn could faul out your plugs and cause your car to die out.

dreadhead89

bump

MONSTERZC

I would change the fuel filter. Also check the o2 sensor my old crx did the same thing. I replaced the fuel filter and the 02 sensor never had another problem out of the car.

90sedan

Sounds like it could be the FITV, did you swap a new manifold on the motor or are you using a known good one? A fitv thats acting up can cause those rough cold starts.

puertoricanboy90

I had an issue just like that, matter of fact i still do. At first i thought it was the fuel filter (which i replaced), dirty injectors (which i took and cleaned, which helped a little bit), or my fuel pump (which died on me so i replaced it) but to no avail. Now i've been asking around and researching and you may want to do a fuel pressure backdrop test. Its where you hook up a pressure tester to your fpr and that will most likely rule out any problems that may have developed. I have not yet found a solution to my car's problem (the exact same as yours), but then again i have stopped trying to fix it cuz i am going to replace the rail and fpr with y8 parts and z6 injectors for my mini me swap this spring. Best of luck to you, but DEFINITELY do the backdrop pressure test!!!

dreadhead89

At least someone has had this problem the only thing havent replaced is that Fi whatever valve. Ill try that FPB test u mentioned. thanks for everyones help.

alx_90ef

haha i have the same problem im runing a d15z1 block(yes i know) with a y8 head. im pretty sure its the coolant temp sensor. cuz i broke the connentor yesterday and prior to breaking it i didnt have that problem at start ups. so you might wanna check that out.

alx_90ef

oh and btw im using everything else stock from my 90 si ecu dizzy etc etc

puertoricanboy90

I don't mean to sound like a dick, but how would a damaged coolant temp sensor affect the engine on cold starts as opposed to when the engine is already warm? If it were damaged somehow, wouldn't the temp gauge on my cluster not work as well? Any help would be appreciated. thx

puertoricanboy90

Could someone please attempt to answer my question? thanks