Very high idle '92 B230FK
 

Hi Guys,

I have been having issues with a '92 945 B230FK. I've had the poor gal for little over a year and have been tinkering on and off but i think i might have made things worse.

I got the car and immediately gave it a service (new filters [oil, fuel and air] {air box latch was missing} and new oil) and cleaned the PCV the associated tubes as best as i could with some degreaser. It seemed to run well but seems to have gotten worse now. The car struggles to start, occasionally wont run on all 4 pistons and when it finally does run it starts of smooth but the idle will climb to about 2000 revs. I have fiddled with the throttle cable stop but the idle will climb and then revert back to normal and then repeat going up and down. I assume this is to do with the idle air control valve but i am not certain.

Please can you guys point me in the right direction or at least help me with trouble shooting the poor sledge.

If you guys need videos of the issue or further descriptions just let me know.

-Rezz

i had similar problems on mine it was the idle control valve.

There are two temperature sensors on that engine. One's for the guage, and the other is to tell the ECU when the engine's cold, so it can alter the mixture. If the engine warms up and the mixture stays as rich as it was when cold, you could get a high idle, and a misfire. It's similar to having the choke button out on an old car when hot. The car almost drives itself, drinks petrol, fouls the plugs and runs uneven.

Other than this, have you checked the plug connector on the idle control valve ? They're usually fine, but if the connections are dirty or rusty, this might cause a problem. With the ignition switched on (and engine off), if you plug and unplug the icv, you should be able to hear it move.

Is the throttle position switch ok ? I once forgot to reconnect it after doing a head gasket on one of those engines, and it ran quite rough.

Another thing that can upset them is the crankshaft postion sensor, which is on top of the bellhousing, below the distributor cap. I'm not aware of them being particularly troublesome, but the wiring connectors for it are under the pipes for the screenwasher jets and if the non return valves leak, water can drip onto the sensor. I had this happen on a 2.3 lpt and it made the engine stall, and put the engine managment light on.

Oh dear.

Oh dear, oh dear.

Oh dear, oh dear, oh dear.

It sounds as if you have a manifold problem - not as in the inlet or exhaust manifold but several problems in one!

First, you should NEVER touch the throttle stop screw, it's factory set and idle speed adjustment is done either with the EICV/AICV or on older cars, a combination of the AICV and idle bypass screw. On early cars, it's purely the idle bypass screw.

There is also a Throttle Position Switch that should make when the engine is in idle conditions (even if the AICV is operating) and as you've played with the throttle stop screw, you've messed up the adjustment/calibration of that as well, further causing yourself problems.

Normal degreaser won't usually touch much of the gunge you get in the PCV and its associated tubes, pipe stubs etc. You need Carb and Air Intake cleaner really.

I'd suggest going right back to basics, starting off by adding 2L of methylated spirits to no more than 1/4 tank of petrol. If there is a 1/4 tank in there, just add the meths and drive it. If there's more than 1/4 tank, wait until you've used enough to drop it to that level. If there's literally only a gallon in the tank, add 2L of meths and no more than 2 gallons of petrol.

https://www.toolstation.com/methylated-spirit/p99550

This will eliminate condensation in the tank as the cause of your poor cold starting/rough running and hunting. It may not be the cure, but will eliminate the possibility. Toolstation is about the best price for a 2L bottle of meths that i know of. Don't be tempted to try one of the small bottles you can buy in various places, it won't do the job - it's all down to the concentration which ideally needs to be about 10% minimum.

Next trick is some Carb & Air Intake Cleaner. Wynns do a good one, available in most auto factors for about £5-6 a can in aerosol form.
Clean the PCV hoses internally with this, including the tiny manifold stubs and the flame trap. On some flame traps, there is a plastic gauze inside - clean this as well.
Refit all the PCV hoses etc, making sure you don't have any split hoses or similar.

Next, remove the hoses from your AICV and squirt carb cleaner into that. Let it soak for a few minutes and while it is, remove the hose from the throttle body inlet, squirt in there as well, operating the throttle butterfly through its range while giving a few more squirts.
Refit the trunking to the throttle body ensuring no leaks and the Jubilee clip is tight - also inspect the hose for splits/holes etc and ensure it is secure on the MAF and now give the AICV another couple of squirts with the cleaner and refit the hoses.

Start the car, giving it a few revs to clear the carb cleaner from the inlet manifold/throttle body and AICV - it will smell a bit and chuck out some odd smoke from the tailpipe but hopefully by now it should be idling at least a little more evenly.

Assuming once the engine is warmed up properly, the temp gauge sits in the middle, once it's up to temperature, switch off and locate the wire (usually red/white) on the 2-pole plug hidden near the coolant expansion tank.
Get a piece of wire, preferably one with a crocodile clip on each end, connect to the wire in this 2-pin plug and the other to earth. The idle speed should drop to about 6-700rpm, if not, adjust the throttle stop screw or if you have one, the idle bypass screw until it is.
As you've already played with the throttle stop screw, i'd go for that first and aim for about 600 rpm.
Now disconnect the jumper wire from earth and the AICV should bring the idle speed up again fairly quickly to (if memory serves right) about 900rpm but might be 700rpm depending on model year.

Next step, switch off, and open the throttle by hand under the bonnet and let it close gently. As it reaches the closed position, you should hear the Throttle Position Switch click, indicating that the switch has detected the throttle is closed. If not, you will need to adjust the switch until it works correctly, ideally with a multimeter to ensure it is in fact making contact.

Now, assuming no other faults, it should be running sweetly again as long as you've followed that in sequence to get to this point.

If there are still running/idling problems at this point then it will need further investigation. Don't be tempted into "snap-diagnosis" because the bloke down the pub says it has to be the MAF or something similar. That will just hurt your wallet and probably won't fix the fault! Follow these steps and you've eliminated all the silly, cheap, usually overlooked stuff that can cause problems. After that, if there are still problems at least you have a level playing field to start from!

Also does your car have a cat on it and do you know if it's LH-2.2 or 2.4 Jetronic injection?

If that non-return valve leaks, it drops water over the distributor, not the CPS which is waterproofed anyway. The water on the dizzy cap is what causes the misfires/cutting out.
The CPS will cause cutting out and non-starting, plus a few other symptoms such as apparent fuel pump failure.

Sorry to butt into thread and also apologies for being stupid but is the AICV the idle control valve ? I'm having slightly rough idle issues and was going to clean that and throttle body.

yes its air idle control valve.

It is indeed - Air Idle Control Valve, sometimes referred to as Electronic Idle Control Valve - EICV. Earlier cars didn't have them but had an AAV instead, Auxiliary Air Valve which was simply an open/shut device that closed as the engine warmed up.

Idle problems are rarely caused by the idle valve. It can compensate for problems but the management is slow to react. Especially if its not getting enough air, you get the 'nearly stalling syndrome'. It compensates but it is expecting a certain idle air flow point and it doesn't learn. Its really to feed in step increases like auto drive engage or AC. These are provided to the ECU and it reacts by opening the IACV a certain amount, then doing fine adjustment if need be.

The engine is getting too much air past the throttle, or possibly a false indication of increased load. Either an air leak or throttle not closing properly, or unused inputs are not grounded. (ag auto or AC if you don't have either of these).

Ok due to a severe case of the lazies I was unable to do any of the solutions provided until very recently. The carb cleaner did a fantastic job at cleaning out the IACV and the motor runs so smoothly now and the idle has been sorted out. I am now only having to solve the bad starting issue. I noticed the other day when testing the IACV that with the key in and turned to "prime" the fuel pump etc i can hear what sounds like dripping (?) or fluid running i assume this is the fuel return from the fuel line.

As for the starting issue the engine is still struggling to jump to life when cranking. It will turn and turn but not start. I might be drawing conclusions when there are none but the engine seems to struggle more if there is more moisture in the air. It is especially bad when it is early in the mornring with the dew and if it has been raining. I hope this helps.

Is there anything about this that stands out to you guys?

Cheers for all the help. I am commited at the moment to get this beast working properly so i can give it the love it deserves.

(also should mention that it is a 97 model rather than 92 not sure what i was thinking when i wrote the post)

- Rezz