Error Codes 22 + 33, High Idle and Running Rich

[chrism]

Sorry roj. Re-read an earlier post to see that the 'modified GM part'(?) was a MAP sensor not an IAC valve. edit: aarrggh...it was the IAC valve after all

Erm...new parts can be wrong tho'. I had a pair of lower links from one of our popular suppliers that were welded together as mirror images that could not possibly have been made to fit short of rewelding the wrongly-welded parts onto the other side; but I gather you've tried at least two IAC units.

Wow when you went back to non-service from service mode that was effective! And yes I agree with Tuga that your ecu seems to be trying, manfully, to correct a surge of excess pressure...

[dapinky]

Well, from the videos, it appears to me that as it runs fine with the IAC valve blocked off, it HAS to be something to do with that.

Whether it is a defective unit (or 3!) or whether it is the ECU signal to/from it, I have no clue - the video seems to show that there is a good old flow through it as when you remove your finger, there is a huge sucking sound (ooh, Matron!) and the revs rise back to the silly numbers.....

...... but I am at a loss as to where to go from here.

What would be the effect of simply unplugging the IAC valve? does it "fail" to a closed position, an open position, or remain where the computer last set it? Does it need a 'completed circuit' to run? I am thinking that if you plug the connector onto one of the spare IAC valves and just position it in the engine bay (earthed with a jump lead or whatever, if required), then run the car (with and without the hole blocked off) - will it hold an idle, and can you see the 'spare' IAC moving????

[Tuga2112]

from the videos.

1 - we can clearly see the idle screw definitly does something (althouhg it seems to reach the full extent of screwing while having a idle that is too high)

2 - the last video. while unplugging the paperclip to me seems a 100% indication it must be something (not necessarily a sensor but most likely it will be) which is being defaulted in service mode, but in "full operation" mode is being set/read which causes the idle to jump drastically.

you need the little box that i have in my car... its just an ALDL cable. but its been wired differently from all others (another one of my little side projects) which allows to read the car and switch it from and to service mode while reading.

that last video has changed my perseption drastically. because there was clearly no outside change that could have allowed more air in, to make the revs change
im also fully convinced the IAC valve is not the problem.

a few thoughts i have at this moment are to make some alterations to your car and elanscan cable in order to be able to get a reading in service mode and another outside of service mode.

also. id be tempted to further investigate (probably ask peter) about what sensors are disabled by service mode.

given your extensive set of sensor replacements. i am expecting the issue to not be the sensor itself. but the wiring.

google/youtube "multimeter continuity test" and "multimeter resistance test" and try adding "car" or "automotive" in the search. if you can start checking the "quality" of each sensor's wiring you may find it.

if theres any sensors that are directly connected to ground nearby the sensor. i would be starting off with those.

[roj]

from the videos.

1 - we can clearly see the idle screw definitly does something (althouhg it seems to reach the full extent of screwing while having a idle that is too high)

2 - the last video. while unplugging the paperclip to me seems a 100% indication it must be something (not necessarily a sensor but most likely it will be) which is being defaulted in service mode, but in "full operation" mode is being set/read which causes the idle to jump drastically.

you need the little box that i have in my car... its just an ALDL cable. but its been wired differently from all others (another one of my little side projects) which allows to read the car and switch it from and to service mode while reading.

that last video has changed my perseption drastically. because there was clearly no outside change that could have allowed more air in, to make the revs change
im also fully convinced the IAC valve is not the problem.

a few thoughts i have at this moment are to make some alterations to your car and elanscan cable in order to be able to get a reading in service mode and another outside of service mode.

also. id be tempted to further investigate (probably ask peter) about what sensors are disabled by service mode.

given your extensive set of sensor replacements. i am expecting the issue to not be the sensor itself. but the wiring.

google/youtube "multimeter continuity test" and "multimeter resistance test" and try adding "car" or "automotive" in the search. if you can start checking the "quality" of each sensor's wiring you may find it.

if theres any sensors that are directly connected to ground nearby the sensor. i would be starting off with those.

I'm in agreement Tuga. I think the IAC functions fine, it's what it's being told is incorrect. Or, the physical set up of the valve is incorrect. I have a 3 videos incoming.

[chrism]

I'm absolutely learning loads from this thread. I was going to '+1' dapinky's post but thought of suggesting trying the IACs out on a car with known 'good' wiring, went out to the garage to find my own IAC and failed miserably to even locate it despite knowing exactly where to look...

Tuga, is this the sort of EScan connector that can help roj get both service and non-service data? :-



I've never used it in service mode but I'm in the South, fairly close to roj and could post it to him if you think it'll make a difference?

Meanwhile we could wait for peteoddcar to turn up with what info on sensors are disabled in service mode.

( Let's hope that he's more confident with this knowledge than erecting gazebos at Cranleigh Classic Car show 2025 - but that's another story for around the campfire of Castle Combe 2026... )

[roj]

How the hell have I turned in to a You Tuber!

So. Some random IAC tests. First up, put the car in service mode, IAC should move to 25-30 steps I believe. I then disconnect the IAC whilst the car is running stopping all comms and power to it. Turn the engine off and so the ECU sends a signal to the IAC to push the pintle out to find end point and then pull back out to 80 steps. Reconnect the IAC and repeat the process. The pintle has moved on further but the ECU thinks it's at 80 steps and continues to push out. Repeat again, etc.

Next two test are with the original IAC valve connected but not sat in the engine. The new SJ valve is sat in the engine (but with no connection) and will be parked at 80 steps so the car will rev high.

I perform the test in normal and service modes. The IAC is getting signals but doesn't seem to be moving to the appropriate spot. Is this voltage based? So as Tuga says, wiring is my next port of call.......

[roj]

Just a reminder/refresh. This is the data that the ECU relies upon to control idle speed.

IMG_7480.jpg

[chrism]

Erm, another thought roj...

Great videos responding so quickly to the dapinky advice offered but looking at the previous graphs I reckon you ought to have left the non-service mode running longer - ie for about 50s - before you might've expected to see some movement?

Btw is that IAC wiring m/plug easy to unplug? Let's wait to see if peteoddcar's sensor data can isolate anything but if my EScan plug is okayed I'd be happy to post it on to you...

[roj]

Erm, another thought roj...

Great videos responding so quickly to the dapinky advice offered but looking at the previous graphs I reckon you ought to have left the non-service mode running longer - ie for about 50s - before you might've expected to see some movement?

Btw is that IAC wiring m/plug easy to unplug? Let's wait to see if peteoddcar's sensor data can isolate anything but if my EScan plug is okayed I'd be happy to post it on to you...

Will do another test later on with your suggestion of running longer in non service mode.

IAC is fairly easy to unplug once you know where to stick your hand (muscle memory). The hard bit is fitting.

Will be great to borrow EScan plug. Thank you. Happy to sit tight until we hear from peteoddcar.

A very kind soul has sent out today a spare throttle body and TPS sensor for me to test. My feeling is nothing will change but 'at least we can tick it off the list'.

[chrism]

It couldn't be anything to do with the secondary throttle could it? :-



There's a vacuum reservoir, a solenoid valve and vacuum actuator all looking very furtive - and the diag shows an ecu connection...

[KenS]

Chris, that Elanscan cable can either do ElanScan OR Service mode, it cannot do both together. The Bluetooth version can do both together.

[roj]

It couldn't be anything to do with the secondary throttle could it? :-



There's a vacuum reservoir, a solenoid valve and vacuum actuator all looking very furtive - and the diag shows an ecu connection...

I have wondered about that but I believe they remain open as normal and then close on full chat. Correct me if I'm wrong. When I took the plenum off, they were in an open position.

I'm not going to dismiss it though.

I've PM'd Pete to make him aware of my idling issue.

[chrism]

Not looking for an argument but I found these on another thread:-

How the secondaries work:
The secondaries are controlled by the ECU through a solenoid. The solenoid supplies a vacuum to an actuator which closes the secondary throttle against spring pressure at engine speeds below 4,700 rpm and/or at low drive speed. Closing the secondaries improves the low speed drivability and the idle.



I know little-or-nothing about sec throttles but these snippets infer that they're normally closed and open up at full chat? Perhaps someone with more 'know' can advise tho'.


And Ken, can't that EScan cable take data readings on service mode and non-service mode independently for comparison purposes? (I've got your bluetooth version but it doesn't 'bluetooth' on my win11 l/top although it does when I try it in win10 on the same l/top. It works okay on my android phone tho'...

[KenS]

So what if the IAC cannot seat fully when it is switched on, due to a damaged seat or crud. So on switch on the ICA drives down to close, fails to fully close, still stightly open and the ECU classes that stop position as count 0. So then susequent positions are physically offset.
I think setting the Idle speed with the bleed screw in-service mode is an important process to calibrate the IAC, so if this has been done but the idle of 950rpm not achieved because the driven count in-service mode has been offset, then the ICA will never be calibrated for normal running maybe further hindered by not setting to a true 0 count on each power up and always having a bleed path due to the poor valve seat.
Can we assume the wiring to the IAC is OK since Roj runs with external IAC show reasonable movement of the pintal?
Any thoughts or shoot downs?

[roj]

Not looking for an argument but I found these on another thread:-

How the secondaries work:
The secondaries are controlled by the ECU through a solenoid. The solenoid supplies a vacuum to an actuator which closes the secondary throttle against spring pressure at engine speeds below 4,700 rpm and/or at low drive speed. Closing the secondaries improves the low speed drivability and the idle.



I know little-or-nothing about sec throttles but these snippets infer that they're normally closed and open up at full chat? Perhaps someone with more 'know' can advise tho'.

Definitely no arguments here Chrism! I'm learning lots.

So when the plenum was off, the secondary valves were open. That's I assume because we had no vacuum holding them open. So if the solenoid valve is dead, no vacuum is allowed through to pull them shut and reduce the airflow.

Does that sound logical?

[chrism]

Perhaps we need VAR...

I agree with Ken that the ecu +wiring seem to be 'working' (okay, after a fashion...)

ps so the bleed screw should be adjusted in 'service' mode rather than 'non-service' mode'?

[TorqueHorse]

Well, from the videos, it appears to me that as it runs fine with the IAC valve blocked off, it HAS to be something to do with that.

Sorry I haven't been keeping up with this thread, as this is exactly where my head is as well!!
If you close off the IAC port, and suddenly the engine runs fine...ding ding ding I think you have found the problem area. Too much air is getting into the system, and it is getting in from that take-off to the IAC. And the only thing that can change the amount of air getting in via that passageway is the IAC pintle (double check my logic, but if it was getting in somewhere before or after the pintle, then putting your thumb over the take-off wouldn't change the idle).

So, trying to do process of elimination:

Is the ECU telling the pintle to be in the wrong place by mistake?
(i.e., a faulty sensor input upstream)
Maybe, but probably not because (I think*) we see from elanscan that all the upstream readings are where they should be. And you can see in your scans that the IAC counts change while the engine runs. And because in your latest video in service mode, the pintle is being told, and trying, to fully extend.
* EDIT: Think again We uncovered an inconsistency in the Power Steering Load flag. TBD on outcome

Is the ECU telling the pintle to be in the right place, but the (correct)signal isn't getting to the IAC?
(i.e. faulty wiring)
Again, probably not because you see the pintle extending when you turn the engine on, so a signal is getting to the IAC

Is the IAC actually doing what the ECU is telling it to do?
Maybe. Seeing it fully extend in service mode makes me think it is doing what its being told. I am on my third IAC valve though where a "new" one didn't work for me.

Is there something physically wrong with the pintle or the receiving area, so that even given the right signal, and fully extending, it still isn't able to properly moderate the air coming down that take-off pipe?
Maybe?? I can't see an o-ring in your videos of the IAC tests. Are you sure there isn't an old o-ring, or other obstruction in the intake manifold that is preventing the pintle from making a good seal when trying to cut-off that air flow? Also, I think it is a pretty tight fit to get the IAC valve to seat well in there. And getting access to those screws to secure it in place is a nightmare. Is it possible it just wasn't all the way in?

Sorry, I'm struggling too to make sense of what you've learned and tested so far.

[roj]

Perhaps we need VAR...

I agree with Ken that the ecu +wiring seem to be 'working' (okay, after a fashion...)

ps so the bleed screw should be adjusted in 'service' mode rather than 'non-service' mode'?

Defo on the bleed screw in service mode. Read about that many a time here on the forum.

Adjusting it doesn't overide the quanity of air. I've got a sneaky feeling about this secondary throttle valve.

I'm going to dissapear around the back of the engine this evening and see if I can manually operate the vaccum actuator with manual pressure.

Wish me luck!

[roj]

Well, from the videos, it appears to me that as it runs fine with the IAC valve blocked off, it HAS to be something to do with that.

Sorry I haven't been keeping up with this thread, as this is exactly where my head is as well!!
If you close off the IAC port, and suddenly the engine runs fine...ding ding ding I think you have found the problem area. Too much air is getting into the system, and it is getting in from that take-off to the IAC. And the only thing that can change the amount of air getting in via that passageway is the IAC pintle (double check my logic, but if it was getting in somewhere before or after the pintle, then putting your thumb over the take-off wouldn't change the idle).

So, trying to do process of elimination:

Is the ECU telling the pintle to be in the wrong place by mistake?
(i.e., a faulty sensor input upstream)
Maybe, but probably not because (I think) we see from elanscan that all the upstream readings are where they should be. And you can see in your scans that the IAC counts change while the engine runs. And because in your latest video in service mode, the pintle is being told, and trying, to fully extend.

Is the ECU telling the pintle to be in the right place, but the (correct)signal isn't getting to the IAC?
(i.e. faulty wiring)
Again, probably not because you see the pintle extending when you turn the engine on, so a signal is getting to the IAC

Is the IAC actually doing what the ECU is telling it to do?
Maybe. Seeing it fully extend in service mode makes me think it is doing what its being told. I am on my third IAC valve though where a "new" one didn't work for me.

Is there something physically wrong with the pintle or the receiving area, so that even given the right signal, and fully extending, it still isn't able to properly moderate the air coming down that take-off pipe?
Maybe?? I can't see an o-ring in your videos of the IAC tests. Are you sure there isn't an old o-ring, or other obstruction in the intake manifold that is preventing the pintle from making a good seal when trying to cut-off that air flow? Also, I think it is a pretty tight fit to get the IAC valve to seat well in there. And getting access to those screws to secure it in place is a nightmare. Is it possible it just wasn't all the way in?

Sorry, I'm struggling too to make sense of what you've learned and tested so far.

Hi TorqueHorse.

All correct on what you've put. Only thing to note is:

• Pintle area is clear, cleaned out with no obstructions. Double checked when plenum was off.
• Pintle is clean as it's a new valve
• The missing O-ring just happened to be off.

Thanks again for your help.

[roj]

Update time...

We can rule out the secondary throttle being open or closed. It made no difference.

I really thought we had it......