1991 745 Car Wont Start Possible IACV/relay issue

[jimmy57]

MAP sensor is in front of driver inside a galvanized metal enclosure. It has a hose from intake manifold running to it.

How did you check the throttle switch?

[745volvowagon]

i dont have a multimeter ATM

i checked the Hoses to the MAP sensor and they Looked fine. i have pretty much checked ALL the vacuum lines and any that needed replacing were replaced.

Well the way i checked the TPS was unplugged the IACV and then unplugged the TPS the car didnt stop idling but when i went to rev the engine the car died instantly. plugged the tps back in and car started right away.

Here is a video of the IACV Unplugged and idling and me revving the engine:


Here is a Video of the UNPLUGGED IACV being Plugged back in and what it does:


UPDATE: So i had a thought, i Cleared the codes Unplugged the IACV and started the car, it did its 500rpm idle, let the engine fully warm up, and then i plugged in the iacv it seemed to take a second to get a signal then the engine went to 1,500rpm at a idle, i popped off the air box iacv nozzle and put my thumb half was over the Opening of the hose to restrict the air, the engine calmed down and idle fine like it should, so i let it keep running, then all of a sudden it started doing that same running rough ect it eventually died and threw a code 2-2-3.

With the iacv unplugged and idling i pulled the injector clips one at a time to see if any of them were working correctly or working correctly and they all made a difference in idle when they were unclipped so i think its safe to say theres no issue with the injectors not firing/working.

Here is a Video of the car Running Fine and then Running Rough shortly dies after this video and It throws the 2-2-3 after this:


im not saying the CTS isnt bad but im not getting any of the symptoms of a bad CTS, that and im not throwing codes for it....im also not throwing codes for for the oxygen sensor.... only throwing codes for the IACV 2-3-3.

i would just go ahead and replace the CTS but nothing is ATM saying replace anything but the IACV per obd codes. ive gone over this car with a fine tooth comb and checked pretty much everything from hoses to fuses to relays to spark plugs to injectors basicly everything and im still only coming up with a IACV

[93Regina]

I'm not seeing any mention of replacing the IAC..

Very good observation; why all he needs to do is to get a 3/4" or so Automotive Heater Control Valve like this, and remove IAC, and insert this unit there. Then, he could manually control idle process with a switch on the dash:-)

[745volvowagon]

i have a IACV coming monday, although i am not 100 that its going to fix the problem

[93Regina]

i have a IACV coming monday

Rex-I/Regina attempts to control idle if throttle switch is set to idle, if coolant-temp-sensor is working, and if IAC is working. Rex-I will attempt to maintain 500 or so RPM for idle, under normal conditions.

IAC is only for idle, when throttle switch is active at idle, then IAC maintains air supply which controls idle.

Here is basic info on Rex=I/Regina.

On a bench, you could manually (via DC voltage) open IAC's orifice, then reinstall back into vehicle, and see if it does a cold start OK, without hooking up plug.

Or, you could trouble shoot it: Idle Air Control Valve.

Note - I have not read those instructions, but give it a try.

Note that Regina and Bosch IACs are NOT interchangeable

[745volvowagon]

The car Will start with the iacv unplugged however when the iacv is plugged in the car dies instantly.

When the car is warm and I plug in the iacv it idles and idles good for about 15 to 20 minutes then it starts running and idling rough again. And then throws the 2-2-3

I do to know if I am just supposed to assume parts are bad without throwing codes for them I don't want to throw money at a cts or tps if I am getting no code for it and having a reason to replace it. Everything point it's to the iacv having the hard star no start rough idle low idle almost like the engine is starved for air and I have already replaced a bunch of parts and checked a bunch of parts.

I have manually put a DC volt 12 to the iacv off the car then put it back on the car however it seems like the motor or the internals of the iacv are shot I don't feel it Humm or buzz.

Yes unfortunately I know about the regina and Bosch difference is insane in price.

I know a decent amount about cars but just feel lost I don't feel confident that I am going in the right direction even though I am following the codes and how the engine acts ect.

[745volvowagon]

Cleaned the Throttle Body Through and Through and polished it
Cleaned the IACV Connector
Cleaned the Intake Hoses up to the AIT
Cleaned the Flame Trap Hose
Cleaned the Flame Trap
Cleaned the Air intake Filter
Cleaned the Air intake box

I tried the Unplugging of the o2 Sensor and unplugging the positive from the battery and i hooked it all back up and still the same issue threw just the 2-2-3 Code

i rechecked all relays manually they all seem to be working.

i guess after the iacv if it doesnt fix the issue i dont know where i will go from there because i am not thing any other codes this is become very difficult. if i am extremely lucky i will get that iacv tomorrow and plug it in and it will idle and i can move on from this nightmare.

in short ive replaced:

distributor cap
rotor button
spark plugs
fuel pump
fuel filter
fuel injector o rings
fuel pressure regulator o rings

Checked all fuses all are good
Checked spark at coil its good
Checked spark at plugs its good
Checked all relays those are working as should Radio,Fan,Fuel Pump
Checked all vacuum lines those are good
Checked TPS Switch Clicks on the minute opening of the Throttle
Checked MAP Sensor Hoses
Checked MAP Sensor Connection

I Have gone over this engine over and over again, so the iacv will be the determining factor as to where i am going to be standing after tomorrow

[745volvowagon]

I replaced the IACV and no Fix DAMN!

I am currently getting these codes

2-2-1 Oxygen sensor not operating Oxygen sensor or intake air leak
2-2-3 Signal missing to/from idle valve IAC Idle air control valve
2-3-3 Idle valve closed IAC Idle air control valve

i am lost someone please give me some kind of idea as to what is going on.

i am replacing the Exhaust manifold gaskets they need it, im also replacing the intake manifold gasket

other than that i am so lost so so lost

[lummert]

Vacuum leak? Have you tried running the engine with the brake servo vacuum hose disconnected and plugged?

[745volvowagon]

car barely wants to run or idle at all. currently i have both intake and exhaust gaskets on the way to me. i have everything apart and ready to \go back together.

i dont understand what the 2-2-3 ,2-2-1 ,2-3-3

i am completely confused on the codes i just dont get it.

i will replace the intake and exhaust manifold gasket, i have checked all vacuum lines, i have checked in short EVERYTHING, THIS IS INSANE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!