I have an 89 IROC with a 350 TPI and it was starting hard. The fuel pump is about 3 years old, might have 1000 miles on it. I know, doesn't always matter, but here it goes. The car has always started hard. Then one day last week it would not start at all. I questioned my gas gauge, so I dumped about 4 gallons in there, and fired right up. Drove it around a bit, no problems. Then when we got home, I parked her outside, then when I was going to put her away, she won't start. Dumped a bit more gas in, and nothing.

So I bought a new cap, rotor, wires. She did start, but did not run without a miss. I have headers so I unwillingly changed plugs also. Plugs was my last resort after the other three did not completely fix the problem. Hindsight I should have also done a compression check. I did hold a metal pipe to each injector and I heard a click on each injector. What should I do next???????????? Do I have a valve that took a ****, or a bad injector that is making noise by trying? What and how should I continue my diagnosis?????????

BTW throws a code 33 aka MAP sensor. I don't trust that though.........

Anything is appreciated
Chris Diedrick

 

Not much on the TPI. You said it is still missing. If so check the color of the spark. Take a plug and ground it out and turn the key to see what color it is. If i remember right should be a nice blue color.

 

Individually un-plug your injection lead... And listen for unballanced idle.. or if you un-plug and no change occurres... That would be the culprit...

 

I assume you mean unplug each injector. I have done that and I was still not able to diagnose the issue. This is frustrating, but can be fixed!!!!!!!!

 

if your ignition module is getting weak could be causing a miss fire. I had that problem when I first got my TA.

 

I replaced the module as well. Made it start, but miss is there now. Sorry I forgot to mention that

 

you fail to tell us what you have done... making use guess what you did do
what is your fuel pressure??? is it constant????
did you check your injector spray pattern????
where is your timing at????
check your pick up coil... if you need specs or how to ask
you say you have a code 33.... why do you doubt this
when did this happen??? what did you change??
sounds like a fuel clog or weak problem... if you have good spark... you never answered the color and pattern

 

to 88gta3508
Your knowledge is way past mine. I am just a shad tree. I did unhook the idle air control valve and then one by one I unhooked each injector. cylinders 5 and 7 had the slightest change in RPM, while the other 6 had a very noticeable change in RPM. My fuel pressure is at 45, timing is fine. Based on what I have tested and replaced, I am thinking bad intake gasket. The car will backfire when I let off the throttle in the few blocks I have driven the car since this fiasco happened. Is there anything else I should look at?
Thanks,
Chris

 

Ok your posting results... disconnecting one injector should not be very noticeable... only slightly.. so now it sounds like you have 6 bad injectors.. did you check your vacuum it should be 18 - 23 PSI

 

What is the best location to hook up my gauge at? Sorry only dealt with Carb'd cars before, finally got ballsy enough to diagnose fuel injection. I opted to use a line off the manifold on the pass side of the intake, the one closest to the firewall. My gauge read 18 and never moved, so according to you it should be fine. Is that a good location, or what now?
Thanks,
Chris

 

FPR vacuum, brake booster, TB, PCV they all should read the same.. 18 PSI steady is good.. rules out valve
you can try propane around the intake to check for leaks... this will increase your idle if pulled in through a vacuum leak...
it does not appear you have a intake or plenum leak