How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask GM Bob Your Own Question
GM Bob
GM Bob, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1037
Experience:  30 plus years. experience as GM technician, ASE Master Technician and GM Certified.
70078276
Type Your Chevy Question Here...
GM Bob is online now
A new question is answered every 9 seconds

Chevy Corvette: I have an '86 Corvette with tuned port injection,

Customer Question

I have an '86 Corvette with tuned port injection, my car runs great when I first start driving, after a few miles (5 to 40) it starts balking and running bad. When the shops scope it, it reads Mass Air Flow sensor. I have had it in 3 different shops, and they can't find the problem. we have replaced 4 Mass air flow sensors 3 of them reman. and 1 GM original used, 2 O2 sensors, computer, performance chip, relays, wires, plugs, plug wires, all with no help.
Submitted: 1 year ago.
Category: Chevy
Expert:  Gary replied 1 year 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 !
can you get this to act up easy ?
will it usually just act up warm ?
when it is acting up is it bogging down ? or the feeling of it running out of fuel ?
do you have a good ohm meter on hand ?
Customer: replied 1 year ago.
It acts up after 5 to 40 miles. When it happens it will run ok at a steady speed, it acts up on acelleration and letting off of the gas. I don't have an ohm meter
Expert:  Gary replied 1 year ago.
and what code number does it keep setting ?
any access to a scan tool to view live data ?
Customer: replied 1 year ago.
It always shows mass air flow sensor
Customer: replied 1 year ago.
Two shops have scanned it, it always says mass air flow sensor. When it happens the service engine light comes on
Expert:  Gary replied 1 year ago.
you know the code number it sets ?
also can you unplug the MAF and in the connector all the female terminals can you tweak over the centers of the female terminals so the centers of each terminal is close off visually so when its plugged into the MAF you know 100 % all the terminals are making good contact with the male terminals in the MAF using a dentist pick or something similar to tweak them over and see if it still acts up
Customer: replied 1 year ago.
I will show this to the tech
Expert:  Gary replied 1 year ago.
ok let me know
Customer: replied 1 year ago.
Codes are 33 and 36, tech now thinks alternator. When it warms up, it starts putting out AC current
Expert:  Gary replied 1 year ago.
that could cause this problem is the rectifier inside the alternator is bad
Customer: replied 1 year ago.
He Has already done the test you suggested
Expert:  Gary replied 1 year ago.
have them replace the alternator if its putting out AC when it should not be
Customer: replied 1 year ago.
Do you have any other thoughts?
Customer: replied 1 year ago.
?????
Customer: replied 1 year ago.
??????
Expert:  Gary replied 1 year ago.
I am out of ideas
lets see if another expert has any ideas
hang on another expert will reply back to you
Customer: replied 1 year ago.
?????
Customer: replied 1 year ago.
No one else has contacted me. What's up?
Expert:  GM Bob replied 1 year ago.
Hello my name is ***** ***** for the wait.If you unplug the alternator does it run ok?If so have you had the injectors resistant checked?There has been a lot of problems with injectors shorting internally.If you find any under 12 ohms I would replace them all of them.Please let me know if this helpsThank you
Customer: replied 1 year ago.
They are all 16 or more
Expert:  GM Bob replied 1 year ago.
Did you check them when it was acting up?
Did you unplug the alternator and did it run ok?
Do you have the part# ***** the two relays for the mass air flow sensor that you replaced?
Do you still have the stock chip?
Customer: replied 1 year ago.
Yes, we checked the injectors when it was acting up. My tech doesn't want to unplug the alternator saying that could damage it. I don't have the part no's of the sensor, but they were both reman., the one we have now is a used gm.
Customer: replied 1 year ago.
He has checked the Alternator while it is acting up, and it shows ok.
Customer: replied 1 year ago.
I don't know if he still has the stock chip
Expert:  GM Bob replied 1 year ago.
You said you replaced the MAF relays.
Here is a bulletin I found that may help.
Here is the link
https://www.dropbox.com/sh/l0tb4fm3li9qopl/AAAGro5zzmvuHbFmK3sCB4jDa?dl=0
Customer: replied 1 year ago.
This has all been done, however we don't have the munual
Expert:  GM Bob replied 1 year ago.
I will opt out see if someone else can help.
Thank you
Customer: replied 1 year ago.
????
Customer: replied 1 year ago.
Please help.
Customer: replied 1 year ago.
Do I not get any more help?