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Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 16873
Experience:  15 years GM master tech
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Chevrolet chevrolet iroc z: Problem with 89 iroc z28 5.7L wont

Customer Question

Problem with 89 iroc z28 5.7L wont go over 2500 rpm after it warms up and when the hazard flashers are on the engines surges with the flash cycle
Submitted: 2 years ago.
Category: Chevy
Expert:  Gary replied 2 years ago.
Welcome! My name is ***** ***** I will do my best to assist you with this problem.Ask me about added features such as phone contact anytime if you wish !
I am sorry for the long wait
what is the fuel pressure when its acting up ?
when it will not go over 2500 will it just bog down like its choking out ?
any codes set in the computer ?
Customer: replied 2 years ago.
Don't know what the pressure is when it bogs down. when its cold it will rev fine and you can hold the rpms without bogging. the SES light is not on could there still be a code? Also prior to my purchase there was an after market security system installed which I don't think even works. the remote does nothing and it has fresh batteries and the light on the remote blinks when you press the button
Customer: replied 2 years ago.
(Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Gary replied 2 years ago.
usually when they get warm and bog down there usually is a fuel issue or possible injector issue causing this problem
at this point you can get it to bog down then shut the car off and unplug all 8 fuel injectors what do all 8 injectors ohm out at ?
then plug them all back in and connect a fuel pressurize gauge to the test port on the fuel rail passenger rearish of the fuel rail and see what the pressure is when its cold then hot and acting up
Customer: replied 2 years ago.
okay I have a volt meter how do I check the injectors. also why would the engine surge in sync with the hazard flashers??? never heard of that....
Expert:  Gary replied 2 years ago.
very tough to say on the surge right now
i sent the phone option for you to accept and we can then exchange numbers if you want
Customer: replied 2 years ago.
we can just keep using the text. thanks
Expert:  Gary replied 2 years ago.
sounds good
so at this point ohm the injectors out all 8 of them like i said then a fuel pressure test
ohming the injectors we are looking for any injectors under 10 OHM's
as that would show a bad injector which on these systems will cause the engine to run very lean
set you meter to OHMS with all 8 unplugged one meter lead to one terminal on the injector then other meter lead to other terminal then write down the OHM reading and ohm all 8 out when the engine is HOT and acting up.shut it off then test them
Customer: replied 2 years ago.
which setting for ohms? 200, 2000, 20k, 200k 0r 2000k
Expert:  Gary replied 2 years ago.
Customer: replied 2 years ago.
3 of them read .01 set on 20k the rest read .00
Expert:  Gary replied 2 years ago.
set the meter to 200
what do they ohm out at ?
Customer: replied 2 years ago.
ok. set at 200 starting with the passenger side injectors readings rear to front are 5.5, 12.8, 15.7, 18.2, drivers side rear to front are 18.3, 3.0, 9.0, 6.4. this car sat in a heated garage for 15 yrs. has original 40k on the car.
Expert:  Gary replied 2 years ago.
any of the injectors under 10 ohms are bad and will cause it to bog down when warmed up once it goes into closed loop
at this point the injectors should all be replaced or at least the ones below 10 ohms
we know right now the ones below 10 ohms are bad and must be changed next
the odds are this problem will go away once they are replaced
as for the surge with the engine running this bad the surge issue should be corrected once the engine runs good
Customer: replied 2 years ago.
I think I should check fuel pressure when its cold and fuel pressure when it is running bad before I throw a bunch of money at new injectors?? Do you agree?
Expert:  Gary replied 2 years ago.
that would be a good idea
make sure the fuel pressure is 34 - 39 key ON engine OFF and 24 - 36 at idle
no matter what the fuel pressure outcome is those injectors will still have to be replaced no matter what
Customer: replied 2 years ago.
what about the MAF sensor? is there a good check for that?
Expert:  Gary replied 2 years ago.
usually a MAF will set codes and you would need an older OBDI scan tool to see live MAF data to know if there was a MAF issue
Customer: replied 2 years ago.
so how difficult is it to replace fuel injectors?
Expert:  Gary replied 2 years ago.
time consuming as the upper intake manifold needs to come off then the fuel rail removed it is like a 50 to 6 hour job
Customer: replied 2 years ago.
okay sounds like I have a project for the weekend. lol... in regards ***** ***** maf sensor is that something advanced auto could scan for?
Expert:  Gary replied 2 years ago.
usually they can NOT comunicate with OBDI systems
a few local small shops or even the dealer still should have the scan tool and or OBDI scan tool connectors to plug into that car
OMDI has been gone since 1995 its getting harder and harder to find the scan tools for these cars
Customer: replied 2 years ago.
one thing i should add when I brought the iroc home and ran it up the road it ran like a raped ape. It then died at the stop sign and wouldn't start again due to a bad starter. replaced that and it cranks everytime. but the garage put like two cans of berryman b12 in the tank and some seafoam. Could too much of that concoction ruined the fuel injectors?
Customer: replied 2 years ago.
or maybe they need cleaned????
Expert:  Gary replied 2 years ago.
can damage the fuel injectors yes but also the car sat for so long internally in the injectors may have had some old gas sludge in them
BUT if they just needed to be cleaned they would have all ohmed out good
being dirty will not change the ohm reading
Customer: replied 2 years ago.
ok i'll change the 4 injectors that are bad and let you know the results
Expert:  Gary replied 2 years ago.
ok sounds good
you can always get me back through this post with any follow up with this question anytime even after you rate us here at Justanswer !