Error Codes 22 + 33, High Idle and Running Rich

[chrism]

Is this what you need Tuga? Mine + pal's are pink + black respectively.



Yep, sorry, I reckon you've gotta bite the over-rev bullet...

Your air:fuel ratio becomes okay-ish after a couple of mins. If you ever decide to go 1499/closed loop your fuel mix pot doubts get taken out of the equation...just sayin'...

[KenS]

Just tried the air bleed screw on a spare throttle body and that unscrews fully, its a little bit snug with the rubber gromment throughout its normal range but actually frees up as the grommet gets above the thread and comes out. Might be worth noting that when fully down (ie air bleed closed) the screw head is 10.6mm +/- 0.1 below the top edge of the housing/lip but I guess this will have variability with machining. If you take it out, worth having a clean rag in the throttle mouth just incase any crud drops through as the screw comes out.
The spare throttle body I have is second hand and I have not use it, it looks ok and has an attached TPS but who knows. If you get to the point of wanting to try another throttle body I am happy to send/loan it, just let me know but at this moment it could add confusion since it is an untested item.

[dapinky]

Without re-reading the whole post, so I may be going over old ground, I have another thought......

..... have you taken the wide pipe off the throttle body (from the inner wing pipe to the intercooler), and watched what happens to the throttle butterfly when you start the engine?

My thought being, that there *may* be something physical which is causing the butterfly to not seat correctly and allow for too much air through, which *may* cause other parts to try to compensate and it all goes high. Obviously, at idle, the butterfly should be completely 'sealed' and only the small amount of air passing through the by-pass in the casting (which is adjusted with the screw).
If the butterfly disc isn't correctly held to the shaft (small screws) it may not be sealing properly.

By taking the pipe off it also eliminates the entire turbo/intercooler/air filter from the equation - just a thought as I am fairly out of ideas.

[Tuga2112]

i believe the air bleed screw is supposed to re-route air that comes from the air filter (theres a small hole before the buterfly valve)

a smoke test wouldnt leak via it, you would require a camera inside the plenum to see the flow of smoke, and then do it again in a "known good car" to compare (basically way too much hassle)

based on both my suggestion and Dave. you have 2 different things to investigate that are potential mechanical failures and both in the same component.

if it was here. i would borrow and temporarily swap the throtle body with a different car for the sake of "check to rule it out" and return the body to it's original car.

im fortunate to have that option, as owning a spare car, as well as a fairly local person with spares (25 miles away) and a few local M100 owners who i may have been able to persuade.

sadly your location seems to make all those options considerably more challenging.

[roj]

Wow! That was tough. Having to sit and watch your car rev it's nuts off in a garage.

Anyhoo. We have data! Cold start all the way up to the fans kicking in.

The IAC valve did come down! Didn't cure it. I attach latest data and hopefully you ElanScan gurus can see any signs.

Timing looks to be way out of range. Agreed?

I'm looking at taking the idle screw out later once the car has cooled down and normal oxygen levels have returned to the garage.

[chrism]

Yep spark advance is still very odd...
Coolant data fine now. T'stat cuts in around 82C and fans kick in around 107C. Spot on I reckon.
Manifold pressure still high on start-up. IAC posn still high and taking ~4mins to drop.

[roj]

Just putting it out there but it hasn't jumped a tooth on the cambelt or one of the cams gone out of alignment? The point at which all this kicked off was back in January. I gave the car some hard acceleration onto a dual carriageway. There was a sudden drop in power, engine light came on and then went off after several seconds. Could something have jumped, put itself out of alignment and now the ECU has recalculated itself (albeit very badly) to keep running. Just a thought?

I think I've exhausted (excuse the pun) all options and theorys.

• The plenum has been off and a new gasket put on.

• The inlet manifold hasn't been off but I would have though we'de see smoke come from that area on the test.

Will still investigate idle screw valve.

[roj]

Just had another play.

• Have attempted to wind the idle screw out but gets so far and becomes stuck, the plastic or rubber gromit seems to be holding it back. I don't want to go any further and make matters worse. I have however been able to wind it in further and it now feels like a definite stop unlike the previous spongy feel from before. I think the grommit has moved around. Distance from top of housing to top of screw is about 10.5mm as per KenS helpful observation. I tried the car with the screw all the way out and it screamed away. Wound it all the way in to the bottom and the revs reduced but we're still looking at 3K.

• I've tried the car without the inlet hose to the throttle body and no difference.

• Regards the butterfly closing, it's most definitely closed.

• Ran the car with the oil dipstick partially out to see if that reduced any kind of pressure. No change.

• I also whipped the cover off the cam angle sensor to give it a 'wiggle' to see if it was suffering the dreaded worn pin. See attached video link. There is movement but may not be a contributing factor. My auto technician seem to think the Cam Angle Sensor was behaving as it should.

[KenS]

I have read through the posts again and seems the IAC keeps coming up and that putting a thumb over its inlet always gets the idle down to near 950. Is this still the case?
If so, doesn't this imply there are no other vacuum leaks and the Idle bleed screw is reasonably OK? If so have you seen the section EMK 4-9 in the Engine Management Manual which details some checks for the IAC, one diagnostic path being a test light to check the wiring harness to the IAC.

[Tuga2112]

that wigles less than my car. i think your ok on that side of things.

Is this what you need Tuga? Mine + pal's are pink + black respectively.



Yep, sorry, I reckon you've gotta bite the over-rev bullet...

Your air:fuel ratio becomes okay-ish after a couple of mins. If you ever decide to go 1499/closed loop your fuel mix pot doubts get taken out of the equation...just sayin'...

is the blue line the one with the high revs ?
if it is, it certainly suggests higher air pressure than the other examples idle.

and not to be repeatedly bashing at the same topic. but you didnt mention the bleed screw.

i do wonder if the bleed screw is doing anything at all, with the car in diagnostics mode, i would try to rule it out by giving it a lot of turns just to make sure the screw itself is doing "something" at all, even if that means confirming that the idle goes even higher for a very short time.
i know the likeliness of it breaking inside is close to zero but not actually zero (i have a friend who had a buterfly valve snapping in half with a old bmw.. )
and finally, just to double triple repeat on the side that Dave mentioned.
is there any play on the throtle cable ? to be 100% sure the buterfly valve is fully closed, and doesnt have any edges chipped or anything like that?

i dont think its possible for the enginge to rev that high with the air suply restrictions undamaged. if the blue graph is from your car, i think the MAP sensor is suggesting theres more air in the plenun than what is normal.

i guess i can start my car and get a elanscan reading as well from iddle to get more comparison data, after work tomorow

[roj]

In answer to Tuga:

Regards idle screw, see my last post, first point. Played with the screw all the way in and as far as I can possibly wind it out. Ran the engine both in and out. Only minor change in revs.

On a previous post, I disconnected the throttle cable. No change.

In answer to KevS:

I’m not so sure on the IAC valve being the culprit. The cold start today shows the IAC moving after getting up to temp. It made it down to 20-25. Engine still ran around the 3k mark when up to temp. This can be seen in the ElanScan data from today.

I will see if I can perform wiring checks. Electrics isn’t my strong point (I.e. I’ve never done this kind of thing before).

I’ll also repeat the blocking off of the IAC inlet to get the revs down. I’m now thinking if I can block it off completely and the car still runs then surely that might help me find a potential leak because the only air entering the engine should be through the IAC and a tiny amount through the needle valve. But where on earth another leak could be I don’t know.

Thanks again both for your help.

[KenS]

Sorry for asking more questions - on recent adjustments of the Idle bleed screw, was it in service mode? Its operation will only be noticable in service mode and earlier it did achieve 950-100 and another time 1100rpm, now if it is closing further maybe it will achieve 950 and the ICA allow that to be held when out of service mode? Are the revs more sensible when in service mode? If they are, the engine can be warmed up in service mode, and that points back at a sensor or poor ICA control. Remember that Elanscan shows where the ECU is commanding the ICA should be, its not sensing where the ICA is.

Car up to temp, fans kicked in a couple of times, stuck the good old paper clip in to activate service mode and brought the revs up to 2000 rpm and let them drop down slowly. Looks like timing was around 10TDC. Adjusted and got it to around 16TDC (timing mark was jumping around a bit). Still idling high. Turned the idle screw in to the point of where I can’t go any further. Idle speed achieved is around 1100rpm. Disabled service mode and she sits there and idles around 1100. Doesn’t sound happy though. Maybe firing on 3 cylinders.:

When performing the old paperclip test and starting the car, she runs perfectly at around the 950-1000rpm. Could this be another sensor? I have a throttle position sensor on the way.

[dapinky]

Aarrrgggghhh! - I wrote a longish reply and then it disappeared!!!!

I'm now approaching from a slightly different angle to see if it helps the 'hive thought process'.....

Starting with the "knowns":-

The engine will start and run under its own settings whether hot or cold - so that means that it can satisfy the 4 conditions required to get that far (even if not in the right proportions).... Air, Fuel, Compression & Spark.

At that point, the idle rapidly increases to 3-4K revs (Is it an instant 'jump' or a slightly more gradual increase over a few seconds - ie, is it like a throttle opening quickly, or a gentle foot down increase?). where it will remain.

It stays at that point whatever the engine temperature gets to, and the temp behaves in a way that would be considered normal(ish).

There are believed to be no vacuum leaks (and even if there were, we wouldn't expect the idle to be this high - maybe 1200 - 1800, but not 3K+)

The MAP sensor has been changed and the part number (and ES graphs) suggest that it is the 'right' part.

The IAC valve has been changed twice without any change to the running, so it is reasonable to expect it to be a 'good' unit........ (what about the wiring to the IAC?)

The ECU has been changed (or am I imagining that part?) with no consequence.

The coil base plates may or may not have been wrong, but are now as per the Manual.

.............

Now lets go to the 'thoughts' and "unknowns".....

For the idle to go that high, the engine requires a fairly high air supply (the fuel is provided to match the air, and controlled by electronics, and appears to 'match' the requirements)..... so where is this air coming from?? and how high a volume is at actually getting into the plenum?

At no point should the turbo or its pipework really come into it, as the car does this well before the 'turbo actuation' parameters are met (90degC, 2,800 revs, 50%+ Throttle)

so - what happens when you try to drive the car? Does it require ANY throttle input to keep the revs at 3K, or does it drop immediately you let the clutch out and add load to the engine? Does the engine (whilst driving) respond to throttle changes/inputs as would be considered 'normal'? (is it driveable, or uncontrolled running??).

[Tuga2112]

im waiting for chris to confirm if the blue line is the faulty car's line.

that appears to be reading about .35 or .40 in the MAP

i was planning on pluggin mine. lets it idle, and then open the throtle enough to get similar MAP reading. just to find out if that amount/volume of air is enough to support 4k revs under no load.

the running theory in my brain (and i suspect most people trying to help) is that theres more air in the plenum than should be, and the ECU is adjusting everthing else to prevent damage. which in turn increases the revs.

the ideal test would be without getting a throtle reading, which is not practical (unpluggin the sensor makes a different reading to "0" therefore not an option)

[dapinky]

I have just had a proper look at the latest ES file (and I am NOT an expert in interpretation of these things, so my observations are from an 'outsiders' point of view......)

The idle is high, whatever happens, BUT things do seem to change at about the 240 second point - the temp drops (thermostat opens), The MAP changes, the idle drops a bit (still high, but drops)

The injector pulse width drops, the spark advance levels out a bit, and a few other bits to correspond to the engine getting to the temp it want to be at......

..... what I also see is that at that same point, the 'Target Idle' is exactly where it should be, and so is the IAC position - BUT - these are ECU expectations, and not necessarily what the car is actually doing.

I see the Throttle is zero all the way along, and I see the TPS varying between 0.4 and 0.42V (not enough to worry me)

I see the Knock counter at 103 incidents, but no retardation applied, so assume it is memory of a previous event.

I'm back to the thought process that the ECU expects things to be as expected at the point of temperature being where it wants it (does that make sense?) It expects this because it 'wants' the idle to be 950 at that point, with an IAC setting of 20 - but it isn't doing it.......

........ everything else is reporting numbers that we should expect.......

....... so i'm back to either a mechanical failure at the throttle body allowing a flow of air that isn't "requested" by an outside influence, or a failure of the IAC valve to regulate the flow of air into the plenum chamber.

I keep coming back to this being the "only" possibilities - as the basics are that air is getting in when it isn't requested by the accelerator pedal/cable or throttle opening. (but may be completely wrong).

[dapinky]

the running theory in my brain (and i suspect most people trying to help) is that theres more air in the plenum than should be, and the ECU is adjusting everthing else to prevent damage.

That's pretty well where I'm at!

[chrism]

Hi Tuga, yes I can confirm that the blue trace in the previous graph was roj's MAP original trace. (edit to dapinky - and virtually immediate)

In this graph I've superimposed his latest MAP trace (in black) and it seems to have fallen to be a lot more 'normal' now:-



So whatever's been recently fixed his MAP has now fallen from ~1.0bar to ~0.28ish bar now in about 50s - a little bit quicker than before when it fell from ~1.0bar to ~0.37ish in about 100s

Still the really high start pressure tho'...

[chrism]

Spark advance still seems rather weird...



..but there's a correlation between MAP and IAC almost as if something is closing (far too) slowly before being properly seated. Again I'm no expert but could that GM modified (?) IAC valve or it's wiring (as per dapinky observation) be causing this issue, I wonder?

And what's going on with that spark advance?

ps absolutely understand Tuga's thoughts about too much air -> very weakened mixture -> very high revs, but what isn't seating correctly that's dragging so much air through when the cold start-up revs are (normally) high? Plus Ken's thoughts about service mode and non-service mode data are unsettling me; I haven't been into a service mode engine run and I didn't know that you could get data. Could there be a mix of data from service and non service mode? A bit confused...

[roj]

Morning gents.

Thank you thank you thank you for taking the time out to help me on this. Most appreciated.

I've run a couple of test and made some videos so you can see what's going on.

My first test was on the EGR valve. My thoughts whilst trying to go to sleep last night was maybe the valve should be closed (but was open) and allowing extra air into the manifold. I performed the Lotus Service manual test on the Solenoid valve for the EGR and it was showing as closed (which it should be). I ran teh car and manually pulled teh EGR plenum up and no change to revs. So both the same revs with open and closed EGR valve.

My next train of thought was to block off the air intake to see if air was entering the sytem anywhere else. Blocking off the pipe closed the throttle body, IAC inlet and needle valve. Pipe collapsed, engine would not start. To me this indicates the only source of air is coming through the inlet pipe.

I then shot a few videos so you can guys can see and hear what is going on.

So first up is the old thumb over the IAC inlet. Engine drops to where it should be and sounds sweet as a nut.

Second up is a close up shot of the throttle body to show it is correctly closing.

Lastly, this one shows the car in service mode, engine temperature is cold/low (only the quick start ups in the garage) and then screwing the needle valve in from fully open to fully closed. Followed by a removal of the paper clip.

Just to sum up. Here is what's been done/changed.

• New Volvo heater valve
• New MAP sensor
• New MAP sensor vacuum pipe
• New gasket for throttle body to plenum
• New vacuum pipes throughout (apart from anything passing through the bulkhead into heating system. I smoke tested from the vacuum resevoir onwards and no smoke appeared in the cabin.
• New MAT air sensor
• New IAC Valve - Cheap £10 job from Lucas
• New IAC valve - £80 'proper' one from SJ
• New PCV Valve and grommet
• New CTS Sensor
• New thermostat and gasket
• New spark plugs
• Cleaned EGR valve, EGR airway into plenum and new gasket
• Cleaned throttle body
• New ECU (that one hurt the most when nothing changed)

Interested to see where this goes next.

P.S.

• Plenum has been off to repair detached knock sensor wire. Refitted with new gasket.
• 3x Earth wires that attach to plenum on cam belt end have been cleaned up before reattaching.

Other points to note

• Original factory Injectors cleaned and refurbed last year (only a few 100 miles done since). RC injectors may have been causing car to pop and bang.
• New cambelt last August (done by reputable specialist)
• PNM Sports exhaust fitted last August

(car ran fine for several months before this high idle saga kicked off)


Prior to me purchasing the car

• New ignition coil in 2023
• New ignition lead set in 2022
• Compression tested in 2023 for misfire issue, new RC injector were fitted

[roj]

Aarrrgggghhh! - I wrote a longish reply and then it disappeared!!!!

I'm now approaching from a slightly different angle to see if it helps the 'hive thought process'.....

Starting with the "knowns":-

The engine will start and run under its own settings whether hot or cold - so that means that it can satisfy the 4 conditions required to get that far (even if not in the right proportions).... Air, Fuel, Compression & Spark.

At that point, the idle rapidly increases to 3-4K revs (Is it an instant 'jump' or a slightly more gradual increase over a few seconds - ie, is it like a throttle opening quickly, or a gentle foot down increase?). where it will remain.

It stays at that point whatever the engine temperature gets to, and the temp behaves in a way that would be considered normal(ish).

There are believed to be no vacuum leaks (and even if there were, we wouldn't expect the idle to be this high - maybe 1200 - 1800, but not 3K+)

The MAP sensor has been changed and the part number (and ES graphs) suggest that it is the 'right' part.

The IAC valve has been changed twice without any change to the running, so it is reasonable to expect it to be a 'good' unit........ (what about the wiring to the IAC?)

The ECU has been changed (or am I imagining that part?) with no consequence.

The coil base plates may or may not have been wrong, but are now as per the Manual.

.............

Now lets go to the 'thoughts' and "unknowns".....

For the idle to go that high, the engine requires a fairly high air supply (the fuel is provided to match the air, and controlled by electronics, and appears to 'match' the requirements)..... so where is this air coming from?? and how high a volume is at actually getting into the plenum?

At no point should the turbo or its pipework really come into it, as the car does this well before the 'turbo actuation' parameters are met (90degC, 2,800 revs, 50%+ Throttle)

so - what happens when you try to drive the car? Does it require ANY throttle input to keep the revs at 3K, or does it drop immediately you let the clutch out and add load to the engine? Does the engine (whilst driving) respond to throttle changes/inputs as would be considered 'normal'? (is it driveable, or uncontrolled running??).

To answer the question on driving. The revs do drop when put under load (release clutch) but when you get going, the car drives itself. Take foot off accelerator pedal, car continues to cruise along. Change gear, the revs jump as clutch goes in and out). Pull up to a junction, clutch in, revs away.

I can no longer drive the car on the public highway as the MOT expired two weeks ago. So no road testing for me. Not unless I can put it through an MOT screaming away at 3000rpm!