Running issues
Thread Starter
3rd Gear
Joined: Aug 2020
Posts: 3
Likes: 0
Running issues
I have a 1989 Chevy corvette
she has a new
idle air control valve
mass air flow sensor
fuel pump
fuel sending unit
fuel pump relay
battery
alternator
spark plugs
wires
distributor cap and rotor
oil and filter
she starts up fine but won’t idle it’s like she’s out of gas but she starts up and has a quarter of a tank
I don’t know what else to do to get her running I’m out of cash app this point
any ideas?
she has a new
idle air control valve
mass air flow sensor
fuel pump
fuel sending unit
fuel pump relay
battery
alternator
spark plugs
wires
distributor cap and rotor
oil and filter
she starts up fine but won’t idle it’s like she’s out of gas but she starts up and has a quarter of a tank
I don’t know what else to do to get her running I’m out of cash app this point
any ideas?
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
Hi
Does the new MAF sensor have a hot wire? does it look the same as your old one inside?
I had corvettecentral send me a MAF that was not the same no hot wire and it would idle rough and stall.
Those type need a ecm chip to support that type of MAF, i got another MAF from another supplier and all was good.
Needless to say i will not deal with corvettecentral again after their attitude, they thought their maf was like the standard one NO IT WAS NOT.
Did you set the tps to 0.54 volts dc with ignition on (middle and top wires) and should show 4.5vdc at full throttle.
Confirm the timing is correct, do not assume the balancer shows TDC make sure you confirm with no1 piston at TDC as the balancer can slip on the rubber bond strip.
Don't forget to reset the ecm via connector near battery disconnect and reconnect, the ecm can get itself lost trying to correct a perceived issue.
Has the base idle been adjusted via the throttle body screw? if not sure you may need to redo a base idle setup (google base idle setting)
Retarded ignition timing can cause rough running and engine speed wandering, should be a simple fix but set the basic parameters first.
the distributor when no1 piston is at TDC should point near the no1 ignition lead, did you connect the leads right remember the dist goes clockwise 1,8,4,3,6,5,7,2, see link below to firing order and cap numbering.
Don't forget to check all cylinders are firing, start when cold run a few seconds and turn off then check each exhaust pipe is the same temp.
They batch fire one side then the other, so you can swap the injector harness from the closest one.
The injector connectors have a thin strip of metal that can be damaged when tugged off the injector by the wiring, i have been there done that...
Good luck.
https://www.corvetteforum.com/forums...ing-order.html
Does the new MAF sensor have a hot wire? does it look the same as your old one inside?
I had corvettecentral send me a MAF that was not the same no hot wire and it would idle rough and stall.
Those type need a ecm chip to support that type of MAF, i got another MAF from another supplier and all was good.
Needless to say i will not deal with corvettecentral again after their attitude, they thought their maf was like the standard one NO IT WAS NOT.
Did you set the tps to 0.54 volts dc with ignition on (middle and top wires) and should show 4.5vdc at full throttle.
Confirm the timing is correct, do not assume the balancer shows TDC make sure you confirm with no1 piston at TDC as the balancer can slip on the rubber bond strip.
Don't forget to reset the ecm via connector near battery disconnect and reconnect, the ecm can get itself lost trying to correct a perceived issue.
Has the base idle been adjusted via the throttle body screw? if not sure you may need to redo a base idle setup (google base idle setting)
Retarded ignition timing can cause rough running and engine speed wandering, should be a simple fix but set the basic parameters first.
the distributor when no1 piston is at TDC should point near the no1 ignition lead, did you connect the leads right remember the dist goes clockwise 1,8,4,3,6,5,7,2, see link below to firing order and cap numbering.
Don't forget to check all cylinders are firing, start when cold run a few seconds and turn off then check each exhaust pipe is the same temp.
They batch fire one side then the other, so you can swap the injector harness from the closest one.
The injector connectors have a thin strip of metal that can be damaged when tugged off the injector by the wiring, i have been there done that...
Good luck.
https://www.corvetteforum.com/forums...ing-order.html
Last edited by gerardvg; Aug 6, 2020 at 07:23 PM.
