I have an 86 Convert. Love the car. SES light is persistent and the car surges. NEW Fuel Pump, Filter, AIC. Any ideas?
I know it vague but I can't think of any other way to describe it. Srts GREAT, then after a few mins SES ligh comes on and it surges from 600 to 1000 RPMS.

 

https://www.obd-codes.com/faq/read-g...codes-free.php

 

I would check the fuel pressure and then check for vacuum leaks. But, probably the first thing to check is codes.

 

It sounds like it happens when the car is going into closed loop which I THINK is around 150 degrees.
Check for codes, then order a FSM for your car so you won’t just be throwing parts at it.

 

thank you Fuel pressure is good. Vacuum leaks….. Oye. I’ll check codes with a paperclip
thank you.

 

Thank you!

 

Got the Code 34. Cleaned the MAF sensor. No Change. I mean 600 to 1100 RPM surging.... Any Ideas? I have a new MAF on the way, but that is just throwing a part at it.

 

git the new MAF sensor. Did zero. But disconnecting it complete, idles smooth?
can I run it like that?
many other ideas?

 

I have an 86 vert as well. My FSM has the following checks for code 34.
Check for loose or damaged air duct
Clear codes....diagnostic terminal not grounded
Start engine and run above 2000 rpm for 1 minute or until SES (service engine soon) light comes on
Stop engine then turn ignition on, ground diagnostic terminal and check codes
Code 34 or no Code 34

CODE34
Clear codes....diagnostic terminal not grounded
Disconnect MAF sensor
Start engine and run above 2000 rpm for 1 minute or until SES (service engine soon) light comes on
Stop engine then turn ignition on, ground diagnostic terminal and check codes
Code 34 or Code 33
If code 34 check for short to ground in circuit 998 which is the dark green wire going to the (hot wire MAS module. If this wire is NOT shorted to ground then the ECM is faulty.
***The burn off relays are located behind the battery on the firewall next to (C100) the large bundle of wires going through the firewall. I'm not sure which is which since there are two relays at that location. The wire you are looking for is dark green and at the center post of the relay.

If code 33 then replace the MAF........Since you have done this already then you are looking at wiring or MAS relay
Good luck..........Also do more searches for code 34. There are some interesting findings on what else causes this.

Also: driving with the MAF disconnected is possible as the ECM has stored fuel maps and will use those when the MAF signal is missing. The engine will not run perfectly but will get you home.
I'm sure others have said this already. Invest in a Factory Service Manual..........you have a 36 year old car with unknown maintenance history.
I find it much faster to look in my book rather than wait for an answer on the forum. This is a great forum and you will get answers but sometimes the answer is not quick.

 

""I'm not sure which is which since there are two relays at that location. ""
86 FSM.
.

 

This is great info! Thank you. I have been running it with the MAF disconnected. Its running pretty darn well? I'll check that wire thank you. I also will replace the relay's and see where it goes. I did invest in the complete FSM so I'm looking for ward to getting it.
I gotta say I love this car, so I'm ready to do what is necessary to keep it right. After I get her running correct, a New top (The one on it is fine but she deserves a new one) is next.
I'll keep you updated! Thank you again!

 

Awesome!!!!!!!!!! Thank you!!!!!!!!!
Even I can understand this!