Brisk

iTrader: (25)

Hey guys. I posted this in TPI but got no results. I have an '88 iroc with a 305 5-spd TPI. The car starts awesome, just touch the starter and it comes to life... except when it is hot.

The starter cranks flawlessly when the engine is hot, however the engine will not catch.. almost like it is starving for fuel? The fuel pump was recently replaced too.. Any ideas? Thanks.

Vader

The cold start injector is not operational above about 120°F coolant temperature (and a given MAT reading). If you are trying to start the engien hot and get no fuel, you may have a problem with the fuel pressure (even though the pump is new, the filter and regulator could be a problem), inadequate injector pulse length, or poor cranking RPM. You've ruled out that last one, so you might want to concentrate on fuel. Make sure the standing pressure is correct. Check it when the engine is hot be be certain.

Make sure the TPS is adjusted correctly, and that the MAF and intake ducts are sealed.

Brisk

iTrader: (25)

Well I don't think that fuel is a problem because it reeks of fuel when I try to start the engine... I am going to check out the things you suggested, I'll have to rent a fuel pressure gauge.

I was talking to a mechanic friend and he told me to check/replace the coolant temperature sending unit. Reason being is my temp gauge on the dash is not working (unknown why) and he figures that the car thinks the engine is cold, so it shuts down the sensors and tries to choke the engine as if it was a cold start.

Seems like a cheap place to start, and if not at least I'll get my temp gauge fixed.

coolcamaroZ28

Brisk, any resolve on this? My friend has an '87 Z that is doing exactly what your IROC is, even down to the fuel smell. I read on a few other posts that clogged or leaky fuel injectors could be the problem. I remember that one of his gauges doesn't work, but I can't remember if it is the oil press or temp gauge. If you have solved the issue, can you let me know so I can have an idea what to do next? THANKS! --John


Couldn't resist posting a pic...


www.coolcamaro.cz28.com

RB83L69

Yup, probably leaking injectors.

Put a fuel pressure gauge on it, and see how fast it leaks down. It should lose no more than 1 psi an hour or so.

Meanwhile, if you floor the gas while trying to start it, the ECM will see that as the driver requesting a "clear flooded engine", and will stop delivering fuel until the RPMs rise well above what the starter will create (i.e. until the engine actually starts), instead of continuing to pump fuel into an intake that's already drowning in leaked-in fuel.

rgarcia63

I recently had a CTS malfunction, I say malfunction because the ECM didn't set a DTC. Smoke was coming out the exhaust, not blue, or white, but gray, and it smelled of raw gas. I didn't have any problems starting it, but I wasn't going to drive it, so I don't know if it would have restarted when hot.

I tested the fuel system for leaks, including raising the fuel rails to put glass containers under the injectors to check for leaks, flow, and good spray pattern - I found no problems.
I removed the CTS, and measured the resistance at 70°F, per specifications the CTS, and MAT sensors should read 3.4k ohms at 70°F, but the CTS was reading 13.2k ohms (185 to 13.5k ohms, 210 to 20°F respectively) which is within range, and why the ECM didn't throw a DTC.

RB83L69

Usually however if the CTS is THAT FAR OFF, you'll have ALOT more problems than hard hot starting; the car will run TERRIBLE, reek mercilessly of fuel out the tailpipes, blacken the back bumper, and you'll be measuring your fuel usage in gallons per mile instead of the other way around.

I'd start at the injectors. Although, the CTS is very very easy to check with an ohmmeter; that should take less than 30 seconds, including opening and closing the hood.

Brisk

iTrader: (25)

I've already replaced the Coolant Temperature Sensor (CTS), and after the first trip to the mechanic I replaced the ECM because he said it was shot... an so far absolutly no change what-so-everl... nor am I driving the car.

I was told to check the injectors already, and to check the EGR valve and solinoid, however I don't have a fuel pressure checker nor a vacuum gauge.. so my car is at the mechanic shop, again! Grr... I like to do things myself but theres times when tools/time won't allow it.

My car has been there for two or three days now and honestly I don't think they've even popped the hood yet, double grr!

I'm stopping in today on the way to work to see what they've accomplished, and if nothing by Friday I'm going to take it to another shop...

RB83L69

It's not the EGR.

It's not the "timing", either; so now we're past the buzzwords.

A fuel pressure checker is dirt cheeep, you can get them at just about any parts store. It's one of the 2 most basic pieces of test equipment that there are for FI cars; the other being a multimeter (also about $12, at Radio Shack for example).

For whatever your "mechanic" is going to charge you to not fix this problem again, you will be able to buy several of each for that; and then you won't have to pay your "mechanic" again if you don't want to.

Go get your car, and stop at the stores on the way back, and put the rest of the money you didn't spend aside, for sending your injectors off to www.cruzinperformance.com for cleaning and flow-matching.

Brisk

iTrader: (25)

So I forgot to write and tell you that I finally got my car up and running again.. what an ordeal. It wouldn't run worth a crap so I started doing some trouble shooting. First off the check engine light was not on, yet it should have been since the car was running on 'limp home' mode. I revealed that the bulb was good and the socket had power. So then I tried to retrieve any codes that were stored by reading through the ALDL plug... borrowed a reader and it wouldn't work.. machine kept telling me that there was no signal. I tried to jump the terminals to flash a code (if any) and read the flashes on the check engine light.. nothing, nothing at all. Sound odd? Ya it seemed very weird to me too...

So I got out my multimeter and started probing the terminals on the ALDL. The plug had no power. Well I ended up rewiring the pigtail from the computer to the 'check engine' bulb and to the ALDL plug. Now I know everything works and has power. Still no readings what-so-ever. I talked to a mechanic at the local dealership and he suggested that I change the computer and chip together.

So I ordered a new computer and installed it. No change. Like an idiot I did not install a new chip at the same time. A few phone calls later I got a chip ordered. No chip in Canada, none in the US. My chip was made and sent to the local dealership from Detroit at the factory. Three weeks later I had a new chip in hand. I plugged in the chip and wow... the car has never run better, like brand new.

This time, however, I ensured that I disconnected the power cable before removing and/or installing the chip. I am assuming that is what caused all my problems, I zapped my chip with a power surge or something when I reinstalled it.

Soon after getting the car running again (and I mean within 45mins) the car died... dead. Now I was able to read codes and see a check engine light (which had never, ever been on since I owned the car, not even when turning the key) The fuel pump quit. So I had two problems when my car didn't run properly... one it was in limp home mode, and two it kept stalling out and not restarting due to a fuel pump on its last legs. Oddly my check engine light is now on telling me to replace my vehicle speed sensor.. something I'll get to at another time.

Anyway I just thought I'd share that story with you and put a resolve to this thread.

rgarcia63

Confused, how old is that recently replaced fuel pump, and how can it be on it's last legs?

Brisk

iTrader: (25)

The fuel pump was replaced in July/August of 2004. It was completely dead when I removed it and bench tested it June 2005.

"Carter" brand name fuel pump.