Help! 1986 engine problems

[aklim]

Is the IAC motor on the throttle body?

Yes it is. You take the entire TB off and take the IAC off and then the few bolts for the IAC housing. Clean EVERYTHING, reassemble and try to reset it using IAC counts if you have a scanner and if not AND you are 100% stock, you can use the FSM method which someone will know about in a bit

 

[Cop151]

Yes it is. You take the entire TB off and take the IAC off and then the few bolts for the IAC housing. Clean EVERYTHING, reassemble and try to reset it using IAC counts if you have a scanner and if not AND you are 100% stock, you can use the FSM method which someone will know about in a bit

Thanks for the help. I will try it, I dont have a scanner so help with the reset would be appreciated.

 

[aklim]

Thanks for the help. I will try it, I dont have a scanner so help with the reset would be appreciated.

Copied from another forum

On an L98 there is no trick:
-jumper ALDL pins A&B, turn key to On and wait a minute or two
-remove the cable connector from the IAC and the jumper from the ALDL
-start the engine and set the idle to 450rpm
-shut off and connect the cable to the IAC
Job done

 

[boomdriver]

Thanks for the help. I will try it, I dont have a scanner so help with the reset would be appreciated.

Did you also replace the 2 MAF relays when you replaced the sensor? Most often its the $7 relay and NOT the $350 MAf
sensor.....



Ck TPS for range and base adjustment.

Ck injector harness for broken wires or shorted wire. Noid lite helps monitor the inj.

Ck EGR with vac pump and mirror for operation to see if its stuck open.


Good Luck, someday it'll be as much fun as you imagined when you reached into your pocket....the 1st time !

 

[Cop151]

Did you also replace the 2 MAF relays when you replaced the sensor? Most often its the $7 relay and NOT the $350 MAf sensor..... Ck TPS for range and base adjustment.Ck injector harness for broken wires or shorted wire. Noid lite helps monitor the inj.Ck EGR with vac pump and mirror for operation to see if its stuck open.Good Luck, someday it'll be as much fun as you imagined when you reached into your pocket....the 1st time !

No I haven't but I going to tommorow. Thanks for the help!

 

[Cop151]

Copied from another forumOn an L98 there is no trick:-jumper ALDL pins A&B, turn key to On and wait a minute or two-remove the cable connector from the IAC and the jumper from the ALDL-start the engine and set the idle to 450rpm-shut off and connect the cable to the IACJob done

The po said he put a new IAC motor in but did not reset it. Could it still cause the problem by not being reset.

 

[aklim]

The po said he put a new IAC motor in but did not reset it. Could it still cause the problem by not being reset.

IN THEORY you can simply install it and leave it. I would always want to know what is going on. Besides, I clean the IAC housing quite often so I would simply set it just to be sure.

 

[Cop151]

IN THEORY you can simply install it and leave it. I would always want to know what is going on. Besides, I clean the IAC housing quite often so I would simply set it just to be sure.

I have tried everything, getting frustrated nothing has worked. I was able to keep it idling when I disconnected the new mass air flow sensor but still ran horrible. The main radiator fan has not been working but when I jumped A&B on ecm to check the codes the fan started running with the engine not running. Could it be the ecm , I tried to locate it but have not been able to. ive looked under the instrument panel but cant find it.

 

[John Robinson]

Don't replace anymore parts until you clean all the grounds. The ECM reads the voltage on the ground wires to determine how to set the engine to run. The codes will only tell you which circuit to look at for a bad ground or a lack of signal it does not tell you if the sensor is bad only a careful diagnoses of the wires will tell you if the sensor is bad. Having been stored invites mice to take up a homestead in the engine bay and while they are there they tend to chew up the wires for nesting material. If you had an FSM you would see that there are a host of things to check before a sensor is declared the culprit in how the engine runs.

Welcome to the world of Corvettes and

 

[Cop151]

Don't replace anymore parts until you clean all the grounds. The ECM reads the voltage on the ground wires to determine how to set the engine to run. The codes will only tell you which circuit to look at for a bad ground or a lack of signal it does not tell you if the sensor is bad only a careful diagnoses of the wires will tell you if the sensor is bad. Having been stored invites mice to take up a homestead in the engine bay and while they are there they tend to chew up the wires for nesting material. If you had an FSM you would see that there are a host of things to check before a sensor is declared the culprit in how the engine runs.Welcome to the world of Corvettes and

It just so happened that earlier today I was trying to locate the ecm and found a mouse (dead) under the dash behind some carpet. Thank you for your advise. I will start checking tommorow. It isnt showing any codes.