1991 745 Car Wont Start Possible IACV/relay issue

745volvowagon · Post by **745volvowagon** » 20 Jun 2014, 07:35

A few days ago the car was starting up and running just fine went to work drove it there and then on the way back to work the car started stalling and not starting or stay starting, popping,backfiring,just overall not starting, and when i did get it to run the car just spuddered to a stop

i immeditately pulled the code and i was getting a 2-2-3 no iacv signal/faulty iacv signal/bad iacv i cleared the code but kept getting the code over and over and over

i have a 1991 volvo 745 with the regina ignition system and regina fuel system. i am getting a no start issue. when i put the ignition in position 2 and i go to listen for the IACV i do not feel or hear any humming or buzzing from it. when i disconnect the IACV the car will start and idle not good around 300-500rpm...then i go to the IACV and i plug it in and the car dies instantly!

i tried switching out the radio supression relays one one for another, i am still getting the problem (unless both relays are bad i dont know)

i tried switching out the fuel pump relay one for another still getting the same problem. i do hear the fuel pump prime and i am getting fuel so i dont believe the fuel pump relay to be bad again i tried 2 a older one and the newer one is from 2009

i cleaned the iacv connectors
i inspected the coil plug wire (its fine)
i inspected the spark plug wires (they look fine)
i inspected all vacuum lines (they look fine)
i Inspected and cleaned the flame trap
i cleaned tps Connector and it clicks as it should (it was running fine no reason to think its pos changed)
i cleaned the throttle body out with carb cleaner
i checked all clamps for air intake
i inspected all fuel lines
i cleaned and inspected battery terminals and connections they are fine

i checked fuse #1 its good
i checked fuse #11 its good
i checked ALL fuses and ALL are good non Blown

Im Getting spark at the spark plugs
im getting spark at the coil
im getting fuel

things i have replaced:

Fuel pump
Fuel pump relay
Fuel Filter
Fuel injector O rings
Fuel Pressure regulator O rings
Fuel Pressure regulator Fuel hose
Replaced Fuel Pressure Regulator Vacuum Line
Oil Change
Oil Filter
K&N Air Filter
Distributor Cap
Rotor Button
Spark Plugs

I am thinking the IACV is bad per no humming or buzzing
the car doesnt start or idle with it plugged in.
Unplugged the car idles poorly
when the IACV is plugged back in the car dies instantly (like its starved for air)

Or it could be the the radio suppression relay but again i switch the fan relay for the other and still getting the same results again maybe they both could be bad? but i doubt that both could be bad although i could be wrong.

the only other thing i can think of that it might be is the crank position sensor however i am not throwing that code, only code i have pulled is 2-2-3 for the faulty Idle Air Control Valve

SOMEONE PLEASE HELP ME PLEASE!!!!!!!!!!!!!!!!!!!!!

Post by **jimmy57** » 20 Jun 2014, 07:44

Does the engine run otherwise but just will not idle?

745volvowagon · Post by **745volvowagon** » 20 Jun 2014, 08:28

Well i pulled the spark plugs and they are carbon fouled and smell of gas from it not starting and idling.

when i get it to idle with the iacv unplugged its really rough. not driveable probably because the spark plugs are so fouled. with fuel and carbon.

when i try to rev the car the revs drop down then go back up this is with the iacv unplugged.

i feel both the radio supression relays click when the ignition is turned on.

i feel the fuel pump relay click when i turn the ignition key to number 2

so it seems that the fuel pump relay and the 2 radio supression relay are fine.

IACV?

Checked the Spark again at the coil Very Strong.
Checked the Spark again at the wires With Screw Driver to Post Very Strong.

from those 2 things i think spark Can be ruled out.

i got some cheap Autolite Spark plugs to replace the ones i had in there that were fouled, with the IACV plugged in same thing Wouldnt start.

With the IACV Unplugged it started right away and had a steady idle of 500rpm up around 1000rpm it was slightly choppy and then above 1000rpm it revved like it would normally smooth no misfire or anything like that.

lummert · Post by **lummert** » 20 Jun 2014, 20:02

Going to have to replace those gas fouled plugs. The only thing that will clean those plugs is a torch.

lummert · Post by **lummert** » 20 Jun 2014, 20:04

NGK spark plugs are also cheap but good quality. I prefer Japanese manufactured spark plugs.

745volvowagon · Post by **745volvowagon** » 20 Jun 2014, 22:08

I replaced them with just some cheap auto lite plugs incase they get fouled out I get better ones later when I fix this problem

The Idue with the iacv unplugged is now steady and revs smooth over 1000th but still does instantly when the iacv is plugged in.

lummert · Post by **lummert** » 20 Jun 2014, 23:46

I'm not seeing any mention of replacing the IAC. Even replacing it with a used on would indicate if it's defective, such as a short circuit.

745volvowagon · Post by **745volvowagon** » 21 Jun 2014, 00:21

No I haven't gotten another one yet so I dnot know if replacing the iacv will help anything or fix the problem.

all I know in short is that when the iacv is unplugged the car starts and revs with it plugged in the car dies instantly.

There's no humming or buzzing from the iacv...to me the iacv isn't working at all obviously.

Post by **jimmy57** » 21 Jun 2014, 07:25

The IAC on that car is a simple solenoid. WHen unplugged it defaults to open and plugged in the MFI ECU pulses ground to control closed period to regulate air flow.

How fast is it idling with the IAC unplugged?

Have you checked the hose to the MAP sensor?

If plugs are fuel fouling there is an issue other than IAC valve.

On Regina fuel system the MAP sensor is the primary sensor with oxygen sensor providing feedback to get fuel mixture optimized. If the hose to MAP sensor gets plugged or comes off the mixture usually goes rich.

The MAP sesnor has a 3 wire plug. Center pin can be probed with a wire slid up into backside of connector so a voltmeter can be used to see the signal. Key on engine off should be 4.5 - 4.7 V. WIth engine idling nicely it will be .8 - 1.1V. Low volts is low load = less fuel, high volts is high load = more fuel. If the signal stays high then it will flood. Unplugging the IAC on an over-rich engine will improve idle as the IAC defaults open and gives more air to lean out the overfuelling. I think a new IAC will leave you with the same problem you have now.
If MAP seems to have correct key off signal and voltage does go lower with engine running then unplug the oxygen sensor and disconnect the battery to let Regina ECU forget fuel trim memory. Then connect battery and leave ox sensor unplugged. Start engine and see if it runs nearly normal like that. If so then the oxygen sensor would be the fault. Oxygen sensor on that car has three wires. The two wire connector is an electric heater and the single wire is the signal. Lean=0.0 -.1V and rich is 1.0 - 1.2 V

745volvowagon · Post by **745volvowagon** » 21 Jun 2014, 07:53

the car with the IACV unplugged idles at 500rpm. if i rev the car it kind of studders a little to 1000rpm and then it revs just fine over that.

my tps switch is perfect i wouldnt see any reason to need to adjust that.

the spark plugs were fouled because with the iacv plugged in the car will not start so its just flooded the plugs.

i checked all of the hoses and nothing is cracked and if it was i replaced them.

the only one i havent checked but may have inadvertently Checked IS the Map sensor, where is it located on the regina ignition/system 740's?

im not throwing any codes other than 2-2-3 and i checked all the other ports and i just get 1-1-1 so all looks good there..

i feel like i crossed a ton of T's and dotted alot of I's however im not certain about anything since i know with volvos what may seem like one issue could be another.

however the fact that the car doesnt start with the iacv plugged in and then if you unplug the iacv it starts, and while its idling plug it back in and the iacv plugged in causes the car to die, to me, it seems like if not the main problem thats a problem.

I Dont think it would be the Oxygen sensor i had it replaced about a year ago with brand new part.