Alright heres the story, I bought a 1990 iroc it is supposed to have a 383 stroker not sure if this is the case or not no reciepts. so i looked at the car test drove it for about 20 min. ran great. drove it 45 min home ran great. then as soon as i got to my home town it started running like poop really bad. when i push the gas it surges and jerks like it not getting fuel. but it is running really rich. like black smoke comeing out the back and makes your eyes burn it gave me codes like knock sensor replaced it. ESC replaced it. i also replaced the cap and rotor. replaced and set the TPS. I ohmed all of the injectors and they tested fine like 14.5. So i tested the fuel press. and it was at 32 psi. thats low so i replaced the fuel filter. started it up and drove it around. ran great for like 20 minn then it started doing it agian please help me i have dumped dollar after dollar in this thing and im wondering if i made a mistake buying a iroc

 

dang, sounds like you already went after the main sources that could cause those symptoms. but after you replaced what you mentioned, did any of the codes come back?

 

Clear the codes, run it until it acts up again, retrieve the codes again.

 

i have cleared the codes, no codes have came up since i have replaced the parts, but still runnin like poop. Could there be something like rust or gunk in the gas tank, because after i replaced the fuel filter it ran great for like 20 min, or could the fuel pump be bad or weak. I dunno i am stumped

 

Check the fuel pressure again.

It should be checked with the vacuum line off of the reg.

 

checked it agian still at like 36 at prime 38 while running, also some times the car will start right up some times it will take 8 or 9 cranks. Then it surges trying to find idle, I have to push gas to keep it running. Also as I was checking all of my sensors I found one missing completely the temp sensor on the intake by the thermostat neck is not there at all and i cant find a wire or connector to plug in to it even if i buy a new one... but the funny thing is there is no ses light on. Could this be a problem....?

 

I know 99.9 percent sure its your fuel pump. OR your fuel pump filter picking up stuff in the tank and clogging it and then when you turn it off it drops the stuff back down in the tank. until it sucks it back up.

 

thanks i will change the fuel pump and see if that is it thanks for the input if anybody else has any ideas i would appriciate it... still dont know if the missing temp sensor will hurt anything any ideas or input on that would be appriciated thanks agian berlin305

 

thanks i was afraid of that, i will change it and see, but i am still confused about the missing temp sensor will it effect anything? and why no light? how do i replace it if there is no wire to hook it up. Thanks for replys

 

get an a/c delco fuel pump. they last.. also check the ignition coil resistance. and pickupcoil.

 

Try the ignition module inside the distributor as well.

 

check to see if the bulb burnt out or if the bulb was removed. when my ses light was on the temp sensor was one of the codes, so yours should be on.

 

Originally Posted by bjm1206
thanks i was afraid of that, i will change it and see, but i am still confused about the missing temp sensor will it effect anything? and why no light? how do i replace it if there is no wire to hook it up. Thanks for replys

check to see if the bulb burnt out or if the bulb was removed. when my ses light was on the temp sensor was one of the codes, so yours should be on.

the bulb works because when i first got the car the ses light was on i replaced knock sensor esc tps and i cleared the codes and the light has not came back on

 

Hey man, sorry to hear about your trouble. My 91' trans am is acting similar to yours. Mine will drive fine, say if you first start it up in the morning and drive for about twenty minutes and then all of a sudden it really, really chokes when you accelerate. I would get a compression test if i were you. I have not had one on mine yet, but i will get one soon. My car was driven for about fifty miles with a loose radiator cap and thus i lost all my coolant. I didn't realize it until i got off the expressway and finally came to a stop. That is when my gauge finally rose in temperature. However, my car does not run hot(160 degrees) and there are NO signs of a bad head gasket or warped heads. Other than , when it chokes under acceleration after it warms up. I have no codes either,but i suspect a possible bad knock sensor or pickup coil in my distributor. I have also been told by several people that my fuel pump could be weak or somehow fluxtuating in flow. Fuel press reg. bad? I am not sure what the hell is going on just yet with mine. Let me know how yours goes. Later

 

I think these third gens have bipolar disorder or something. i have replaced everything only thing left is the fuel pump and the missing temp sensor that i not sure how im going to fix because i cant find a wire to connect to it so if any body has a color wire scheme or can give me a hint on how to fix this so i find it off the ecm or some thing. I dont know what to do.

 

Hey dude, yeah that really sounds like a bad temp sensor all right. Black smoke,huh. Well, I will look at my car later and let you know what color the wires are. Mine is right under the throttle body on the front of the engine. Are you sure that this engine you have is an original TPI motor? Maybe the guy used an older engine and threw the tpi stuff on top? Are all of your other sensors in the usual places on the block? If you do have a TPI block, then is there a plug where the CTS should be?

 

yup jet black smoke when i hit the gas and it smells real rich. thanx alot man check it out if you would

 

Mine was running rough about a year ago and I went through everything. After checking the compression on one of the cylinders, I unscrewed the hose and it was full of gas. I pulled the fuel rail and found that the injector was stuck open.

I've been told that the resistance will not be affected by being stuck open so you can't use good resistance as a guide.

Just a thought.

 

You need to figure out where the temp sensor is. Find a diagram for your wiring harness. Start with your computer and trace your temp sensor wires to where they go.

 

ok does anyboddy know the wireing scheme for 1990 iroc

 

http://www.alldatadiy.com/buy/index.html

 

Hey dude, found the wires to the coolant temp sensor on my car. one is yellow and the other is black. Does your car have a plug where the cts used to be?

 

Hey dude, found the coolant temp sensor wires on my car. One is yellow and the other wire is black. Does your car have a plug where the sensor used to be? If that sensor is not present i don't believe that you fan will come on!

 

Thax that helps alot. There is no wires near or even under the engine bay that color so they must have cut the wires at the fire wall or something. But since I know the wire colors I think I can trace them from the ecm now. I don"t know what they have done but this is such a pain in the A**. They have hacked this car so much. But its a diamond in the rough. But my fan does come on tho. So I'm confused about that. Unless for some odd reason they got a chip burned to omit that sensor. And still make the fan work.

 

On my 91 I have a temp sensor for the ecu in the intake, and one in the block for the fan. The one in the block is one wire, intake is two. And there's no ecu that I know of that can run without a temp sensor.

 

so how is that posible the sensor on the side of the block on the passenger side is there with one wire going to it, but the one on the intake by the thermostat is not there just a hole, and i cant find wires any where, and there is no ses light showing that it is not there. I know the light works because it has come on before when my esc went bad. I dont know im confused

 

You need to get a wiring diagram for you car, and trace things down from the ecu pins. I like using alldata. The link I provided for you on post 21. Or you can probably go and by the book for the car. Take some pictures of the engine bay and post them here in your thread so we can see what it looks like, because I have a feeling something isn't right.

 

Ok heres some pics the engine bay is kind of a mess right now but i did the best i could with the pics. There is two plugs that i found on the passenger side laying on the header i dont know what they go too

 

The temp sensor is in the front side of the intake, close to the timing cover and water pump. That hole you pointed out is just a extra hole or something. And those other connectors are probably for the smog diverter valve.

 

Wow thanks, good idea on posting the pics, so i will go look for the real temp sensor. But any other ideas why it might be runnin rich and surging at idle, maybee bad o2. there is no cat on the car so i thought it would be pointless to change the 02. am i right or not. And do i need that smog diverter valve that you were talking about.

 

There's lots of reasons for rich / surging. Most of the time when your ses light is not on the sensors are ok. So start checking things that the ecu can't, like fuel pressure, vacuum leaks, plugs, wires, cap / rotor, all the simple things. If someone put a aftermarket cam in it without having a custom chip made it will surge and basically won't run right depending on the size of the cam. As for the connectors not hooked up, you don't necessarily need the smog pump stuff if that's what it really is but without you getting a wiring diagram and checking it, we can't really trace it down like I said earlier. And you won't pass the emission's test without the smog stuff either. Get a diagram and check that stuff out.

http://chevythunder.com/fuel%20injec....%20pg%20A.htm

http://chevythunder.com/since_its_inception_in_1985.htm

 

thanks i dont have to worry about emissions yet i live in michigan and we dont have emissions. i dont know if it has a cam in it or not i dont know how to tell without tearing it down and measureing. i know the fuel pressure is low its like 32 psi would that possibly make it run rich i know it could make it surge. thanks morepowerrjoe all of your help is very much appriciated. i do have a fuel pump im just waiting for the right time to do it. the right way

 

Yeah that fuel pressure is pretty low. You better replace that pump before anything else. Good luck.

 

yeah thats pretty low fuel pressure. i would check the timing also

 

Hey dude, that hole is not for your temp sensor. Like the other guy said , your CTS is on the front of the block under the throttlebody. It should have two wires coming out of it . One is yellow and the other one is black. As for that other set of wires in your pic. I will check my car again and see if they look familiar. They should be hooked up whatever they are.

 

Yea thats what i thought, they are there for a reason thanx for the help

 

All those lines do is open and close a valve for the smog pump. You don't even have the smog stuff to hook up. In your picture it looked like you had headers. If so then your smog tubes are gone, their on the stock exhaust manifolds. Is the smog pump underneath the ac compressor? or is it gone? That stuff does not effect the way it runs without it hooked up.

 

the threaded hole is for a different application, on corvettes there's a cable gutter that runs there to hold the injector harness

Here you can see the square black gutters on the inside, between runner elbows and valve cover



the 2 connects are both for the AIR switching valves (black box above manifolds, removed on yours hence then being loose) They are behind the little cover on the assembly (whole thing missing on yours)

 

THANKS FOR ALL OF THE HELP FROM EVERYONE YOU REALLY CLEARED ALOT OF THINGS UP. MY NEXT QUESTION IS... ARE MY INTAKE RUNNERS AFTER MARKET OR SOME DIFFERENT STOCK OPTION. THEY JUST LOOK DIFFERENT THAN IM USED TOO. I KNOW I SOUND LIKE AN IDIOT BUT I AM VERY NEW WITH THESE CARS AND I REALLY DONT KNOW WHAT I BOUGHT. BUT I THINK I GOT A GOOD DEAL AFTER I WORK OUT THE KINKS.

 

you dont sound like an idiot. but yes, those are aftermarket simease runners. i wish i had some lol. and i like that smooth throttle body duct piece too. and you have headers, but im sure you already knew that lol.

 

yea i knew i had headers, i guess that throttle body piece was custom made by some fabricator. i dont really know much about this car but it supposed to have a 383 and it ran like it did when i first bought it. i had a mustang with a 347 stroker that ran low 12s and this car would eat it. but now i cant get it to run right. i bought it in ohio and apparently it dosent like michigan. agian thanks for all the help. now that i have switched sides to chevy i need the help.

 

It is the injectors sticking open. Replace them with higher capacity ones. And not Accel!

 

you think so, which ones do you suggest, what flow rate, i dont know what is in there. as far as the capacity of them.

 

plan on replaceing fuel injectors what ones do you guys suggest what flow rate, brand

 

It doesn't matter what brand.LOL. I am currently using Ford 24 LB/hr injectors in my 91 350 TPI. I think they came out of a Mustang cobra. It will make no difference if they are 24 lb./hr and the factory ones are only 22 LB/hr. They will still work. Honestly, just buy what you can find cheap. Make sure they are at least 22 LB/hr though if you have a 350.

 

Ok thanks, so i can get some out of a mustang and they will fit, somebody told me i would have to modify them to work in the tpi setup

 

Yeah, you can get some out of a mustang,but just make sure they are from a COBRA or Ford 460 truck motor(same part #). I am assuming you have a 350 tpi motor or larger ,right? Ok, because i know that the 305 GM tpi motors are only 19 lb/hr injectors and the 5.0 mustang GT are only 19 lb/hr too. If you do decide to use the Ford injectors , they are the blue ones. The blue ones are always the 24 lb injectors. It goes like this for Ford injectors: grey=14 lb, orange=19 lb/hr, and blue=24 lb/hr. The reason i tell you this is because you can't really go by part numbers on the Ford injectors. The Ford 24 lb/hr injectors are a popular mod with third gen owners.

 

I don't know who told you that you would have to modify those Ford injectors to work. That is a bunch of bull kakka dude.Just make sure you put a little engine oil on the injector's o-rings when you install them. Also, reuse your old injector clips from your old injectors. https://www.thirdgen.org/injectorswap Here is a link to explain how to swap out your injectors. Later

 

thank you very much, that really helps alot.