I have been trying to figure out what is wrong with my 1988 Firebird 2.8 MPFI.

It has been having a habit of not starting lately after driving awhile. The first start of the day it starts right up, immediately! Then as I drive down the road, after 10-15 mins, it starts to run like crap, even die a few times. Then it won't start. I can come back 5 hours later, and still won't start. If I wait until the next day..... it fires right up!

The guy I bought it from told me he had this problem once with the car. I drove it occasionally for 5 1/2 months since I bought it without a problem, but now it is doing it all the time the last couple weeks. I changed out the coil, and then the ignition control module. Still same problem.

The ECM diagnostic blinks code 34 for MAF sensor, but I don't see that making the car not start, just run like crap. I will change the MAF sensor anyway, but I think the real problem is elsewhere.

Last time it didn't start, I undid the air intake hose and sprayed starting fluid in the intake as I turned it over, and it fired and almost started. So now i know it has spark. BTW, It also has a new fuel filter.

Could it be: fuel pump, fuel injector/s, some stupid *** sensor/module dealing with the fuel/intake delivery?

Any help is appreciated. I really don't feel like blowing any more money I don't have on any more parts I don't need.

Thank you!

 

This seems to be a common problem lol...but it could be alot of things...you have a good start tho...

Since you already read that other thread you know about doing a full tune up so i wont bother with that...

I would get yourself a timing gun, spark plug tester, and fuel pressure tester. All together depending on what exactly you buy it could add up to a lil money but you will use them for your car and any car in the future so its a good investment.

I would do this...
-Check to make sure you have spark at all plugs
-Make sure the wires are on the cap in the right order(refer to Hanes manual...dont assume it was right before your changed it...been there done that lol)
-Check your fuel pressure to see if your in the right area or at least pretty close
-Check your timing and return it to stock config(inless your car is modified and needs to be ran at a certain degree)
-Then do a search on this thread or under general engine tech about the common sensors...it is possible they are causing the problems
**usually a faulty sensor will throw a code but not always
Sensors to check
-EGR
-O2
-TPS
-MAF or SD depending on car
-Coolant temp(this is what caused mine to not start...also had a bad computer)

Thats a good start on what to check. Most of those are cheap except for the EGR and MAF...those are pricey

Just a lil story on the coolant temp...my car would run great for the first couple months i had it(well i thought it ran great...never had a third gen before)...then it wouldnt start sometimes...never threw a code tho....i ended up finding out that it was the coolant temp sensor...If a computer senses the coolant temp sensor is reading wrong it will stop flow of fuel and spark to the motor that way you dont blow up your motor. This false reading will also cause the motor to jerk and cut out when your driving(at least it did for me)...i replaced the sensor twice cause of this then found out my computer was bad(i took it to the local shop cause i couldnt figure it out...they diagnosed the car and found the computer was bad...got a new one put in and its been good ever since) NOW my car runs well. It pulls pretty well and runs a decent quarter for a mostly stock six with a huge system in the back.

Hope that helps...

 

do you remember how much a new computer was? And did you put it in or did you have a shop put it in. . . would you be able to give me rough estimate on the price to have someone put it in? Last thing....so the coolant tep sensor helped it out...how much was that?

told you that I would be using your brains man lol...


Thanks again man...

 

Computer was 150...shop price...and i had them put it in...they did it for 270.45...idk i could have done it alone prolly but i was pissed and had to get the car towed anyway(it died in the road)....if your car will only start if you floor it then its either the coolant temp sensor;which is 30 bucks btw or its something with the computer...thats if you have already tried all the things i listed above lol

 

Fuel pump relay > 20 bucks > solved my problem! I did a complete tune, replaced 02 sensor and all kinds of stuff and nothing helped untill I replaced the Fuel Pump Relay.... Hope this helps you solve your problem.

 

youll know if the fuel pump or relay is dead...turn the car to on position...you will hear the pump kick on....if it doesnt...then there is your problem....but like i stated do a fuel pressure test...if your fuel pump is not kicking on you should have no pressure...or at least not much

 

When my relay was on it's way out it was acting up intermently.... If there was bad fuel pressure it would most likely happen all the time if the injectors are plugged.... Torque22 problem is intermtten. Check the pressure for ShIIIIttts and giggles > but really change the Relay. Only 20 bucks!

 

ya good point...for $20 what the heck...i might go do mine just to be sure