Error Codes 22 + 33, High Idle and Running Rich

[roj]

I read a post about different MAP sensors a few months ago and didn’t consider it. I purchased the part from SJ so assumed it will have been the correct part. I will have a nosey tomorrow. Thanks for input. Most appreciated.

[roj]

So today I've conducted a test with ElanScan connected. My test was to see if disconnecting the MAP sensor was making the IAC valve move and resulting in less air going through and revs coming down. In short, the answer was no. IAC shows no real sign of movement until the engine is switched off and it checks it's position and parks back up at 80.

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I have no CEL light on but ElanScan does flag up MAP High on. Most odd.

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I've also taken pictures of the new and old MAP sensor. New one is a Delphi unit from SJ. I've tried both units and they both do the same thing with revs dropping when MAP disconnected and then straight back up again after 2 or 3 seconds. (see previous posts a little earlier).

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Double checked TPS sensor with engine off and with engine running. No sign of throttle movement and no change in voltages (when running).

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Daft question or thoughts.

1. Could there be a blockage (as opposed to a leak) as disconnecting the MAP sensor temporarily allows the air pressure out until it build up again.
2. Could my auto technicians theory of possible alternator badness be throwing electrical gremlins to the MAP sensor (but nothing else it would appear)
3. Have we got a dodgy electrical connection to the MAP sensor. If so, what's the best way to test that one out? Gotta ask as I'm rubbish with electrics.

I attach ElanScan data if anyone has the time to have a look.

Look forward to any response/help. Thank you.

[dapinky]

Well, a Delphi PS10082 is a 2-Bar MAP sensor for various GM cars, so I can't see it causing problems......

[KenS]

Hi Roj, just a thought, do you have that filter in the drivers end of the plenum that feeds the MAP sensor? It hasn't been replace with a plain elbow without filter has it?

[roj]

Plain elbow without filter? A filter? This is all news to me!

I assumed all was good with this as the car ran fine at the start of the year and nothing appears broken. I’ve read one or two here have broken their elbow joints due to being brittle through old age, etc. I thought there might have been a blockage or an air leak on it but it must be clear as you can hear the air coming out when I take the pipe off. Smoke tests shows no leakage.

If you have any more info on this then please do share. I’m all ears.

[KenS]

Sounds that the feed to the MAP sensor is OK. I was thinking that if that filters purpose was to damp the response of the MAP sensor then if the filter had been replaced with a straight through connection maybe the MAP response was too dynamic causing a noisy MAP signal to the ECU. But as you say, the car has run correctly in the past with this area unchanged, so this is not an area of concern and the thought is shot down. Do you have a warm-up Elanscan log from ambient temp for several minutes with no throttle action? Is it agreed that the ICA is not being driven down as quickly as is should by the ECU, so something is fooling the ECU to keep the ICA count high?

[chrism]

I agree with KenS that a static warm-up would be more relevant - at least until the t'stat opens - and yesterday I was looking at the original roj data (blue) where I think there's a bit of a warm up period.

I superimposed my own (black) and a pal's (pink) IAC data and whereas another set of warm-up data would be welcome I think this might point to the agreement that Ken's highlighting. (I'm not sure I really understand the 2nd IAC /MAP correlation tho'...)



In the same vein I've superimposed MAP data which, I think also supports Ken's thoughts that the MAP sensor seems 'normal':-




Hope this helps... Btw my black data is from a '90 1499 SE and my pal's pink data is from a '94 1499 S2.

ps Am I right in thinking that such a high initial manifold pressure will weaken the air:fuel ratio and cause the high initial tick-over?

[chrism]

...and there's definitely a correlation between IAC posn and revs:-



I'm not sure how the ecu controls the IAC valve but can it be sticky?...isn't there a spring that causes some movement in response to an ecu command? Is it possible to (cheaply) substitute it? ie to get your hands on (say) a used example from a breaker...

[roj]

Hmmm. Bit stuck as to what to do next. If I attempt to gather a static warm up data then the car will be sat there screaming its nuts off!

Surely 3500-4000rpm from cold is not going to do it any good.?

[roj]

...and there's definitely a correlation between IAC posn and revs:-



I'm not sure how the ecu controls the IAC valve but can it be sticky?...isn't there a spring that causes some movement in response to an ecu command? Is it possible to (cheaply) substitute it? ie to get your hands on (say) a used example from a breaker...

It’s got a brand new IAC valve on it. The hole-port it goes into has also been thoroughly cleaned out. By the time I finished, this car will be factory fresh!

[chrism]

Yep, sympathize with the difficulty of a 'rev-yer-nuts-off' start up...

Long thread...did you check the spark advance? Again mine + pal's superimposition over your blue data:-

[roj]

I did and it looked to be in the ballpark. First time I’ve done this so learning on the job. My timing looked like it was ‘jumping’ around all over the place. Not a constant repeat point showing up. Will give it another check this week.

[roj]

Anyone got any thoughts with the 'MAP High Error'?

Is that just the MAP sensor reporting back that there's too much pressure in the manifold? Where as a 'MAP low' is reporting low pressure. The errors aren't related to the condition of the sensor but are the conditions the sensor is reporting back with.

So a quick Google on high manifold pressure brings up the following (take with a pinch of salt, this is most likely AI talking).

-----------------------------

External Restrictions:

Clogged Air Filter:
A dirty air filter restricts the amount of air entering the engine, causing a buildup of pressure in the intake manifold.
Exhaust Restrictions:
Clogged catalytic converters or other exhaust system issues can impede the flow of exhaust gases, leading to higher pressure in the intake manifold.

Internal Issues:

Faulty MAP Sensor:
The MAP (Manifold Absolute Pressure) sensor measures the pressure in the intake manifold. If it's faulty, it may register a higher pressure than actual.

EGR Valve Issues:
The Exhaust Gas Recirculation (EGR) valve can malfunction, causing improper recirculation of exhaust gases, potentially leading to higher manifold pressure.

Throttle Body Issues:
Problems with the throttle body, such as sticking or improper opening, can affect airflow and pressure.

Other Factors:

Engine Load:
High engine load, such as during acceleration or climbing, will naturally increase manifold pressure.

Altitude:
Higher altitudes can also affect manifold pressure, as the air pressure is lower, causing the engine to work harder to draw in air.

Turbocharger Issues:
In turbocharged engines, issues with the turbocharger itself, such as a wastegate malfunction, can lead to excessive boost and high manifold pressure.

-------------------------

I think I've ticked off all of those but I'm having thoughts of if there is any issue with the turbo. Google results come back with:

"No, a car turbocharger generally doesn't increase manifold pressure at idle. At idle, the engine is producing minimal exhaust gas, and the turbocharger's turbine and compressor are spinning slowly, resulting in minimal or even a slight vacuum in the intake manifold. The turbocharger's primary function is to increase boost pressure (above atmospheric) during acceleration and higher engine loads, not at idle."

So I guess not but just putting it out there.

[KenS]

EDIT PLEASE DISREGARD THIS, I HAVE CROSSED OVER THE PLOTS SO INCORRECT. SORRY

I am wary of throwing too many thoughts at this so more for discussion first rather than going and changing hardware.
Looking at an earlier plot 439DJH_20250411_COLDSTART-AND-DRIVE_NEW-IAC-VALVE.ecu and comparing it with a couple of reference plots there are two that stand out:
The Target Idle RPM where the black line is roj's, indicating that the target is higher than the normal 950 rpm when warm, as met by the other 2 reference plots

Plot1.JPG

The Coolant Temp, where the black line is roj's, showing the stable temperature as about 65degC, lower than the reference plots that are nearer 80degC

plot2.JPG

So could this be indicating the engine is being overcooled or the CTS sensor is bad? If the ECU thinks the car is still warming up it explains why the target Idle speed is still high and why the car may be running rich?
Whats peoples thoughts/ And probably need to see if this is consistant on other plots before taking it as fact.

[chrism]

KenS got a reply in before me but that CTS thought sounds compelling. Time for another EScan methinks.

Another 'put out there'. My '90SE (ex-9239) is now the proud recipient of a 1499 upgrade via one of RonR's dual chips.

I still have Ron's dual 9239 /1499 processor that I trialled when he was making earlier chip magic. I wonder if it's worth your trying this 9239 map in your current ecu to rule out any map problems? It'd be cheaper and easier than substituting the ecu in an attempt to iron out any problems (if you suspect any) that end. (Mind you, it wouldn't isolate any non-map problems that your ecu might have...)

I'm just thinking that some kind of ecu substitution might be worth looking at in order to make absolutely sure that your new IAC valve is being properly actioned by the ecu - and that the problem is, indeed, engine-side.

Even used non-1499 ecus are incredibly pricey if you can get hold of one . Long shot but perhaps a pal on the IOW or local area has a spare ecu that they wouldn't mind lending you? The 1499 ecu is a fraction of the price of yours and there could be a chance that a local 1499-upgrader on LEC might have have bitten the bullet to replace theirs as a total investment in 1499-ism? I personally considered that move; the emissions relief alone has meant that I'd never consider any revertion to open loop.

Another thought: Could your fuel mix pot be malfunctioning and/or stuck on a weak setting?



I only have one non-1499 (blue) EScan to compare but rather than the high MAP causing a weak mixture effect I wonder if a weak start up mixture (allied to your original spark anomaly) could be the tail that's wagging your IAC dog?

[KenS]

Whoops, sorry, I have crossed over plots on my earlier post please disregard, back to square 1.

[chrism]

Does this add anything Ken?



roj's pink original data definitely shows that his coolant's struggling to get up to t'stat temp. The other's are getting there within 5-10mins.

peteoddcar's recent post about an alternative and very affordable CTS upgrade might be a godsend here if roj's CTS sensor is duff, I wonder?

Again I reckon a more up-to-date EScan wouldn't go amiss...(bearing engine over-rev in mind tho' )

[Tuga2112]

i read the first couple of posts after my last reply and only glanced at the rest. but a thought ocurred as it seems like all sensors are fine.

one thing to note is that the IAC valve position on elanscan is not "where it stands" its actually "where the ecu it telling it to be"
however considering you changed them more than onse, and the Revs are being affected by the ECU command to change its position, I am inclined to accept the IAC valve is fine.

i know you mentioned you done vacum tests. (i think i recall that topic a month or 2 ago) and we both found the EGR minor leaks.

one thing i want to clarify, is if you opened the throtle body when doing the test to allow the fumes to flow easily "everywhere"

what has occured to me. is that the idle air bypass screw may be damaged, or unable to close far down enough. this is a mechnical point of failure which would explain why all sensors are fine... and you still get the idle too high.

i dont know if the additional air pressure from the "not leak" would be readable from the MAP sensor at idle. but definitly something worth checking. may i ask Chris to look at those values in between hes multiple data files.

given the amount of different things already tried, may be worth removing the thotle body and having a look at it in the workbench, Unfortiately your not really in a practical place to just try swapping the bosy with someone else's car to give it a test.

[roj]

ChrisM and KenS thanks for coming back to me.

CTS was changed on Saturday (16th Aug) along with thermostat. No change.

New ECU (from SWLC) was purchased 2-3 weeks ago. No change.

I haven't done a cold start up to fans kicking in Elan Scan recording since the CTS or ECU have been fitted.

This sounds like the most logical thing to do now so we can see where we stand with the car. It's the 4000rpm sat there that puts me off doing it. I guess I have no choice.

As to fuel mixture pot, I haven't touched that at all. It could be completely out of whack as you will see from my pictures earlier in the thread, this thing was gunked up in throttle body, IAC, etc and maybe the mixture was adjusted to compensate for that?

It certainly runs rich. Stinks when returned to teh garage, drinks fuel and I have a sooty tailpipe along with bits of soot on teh back bumper.

[roj]

i read the first couple of posts after my last reply and only glanced at the rest. but a thought ocurred as it seems like all sensors are fine.

one thing to note is that the IAC valve position on elanscan is not "where it stands" its actually "where the ecu it telling it to be"
however considering you changed them more than onse, and the Revs are being affected by the ECU command to change its position, I am inclined to accept the IAC valve is fine.

i know you mentioned you done vacum tests. (i think i recall that topic a month or 2 ago) and we both found the EGR minor leaks.

one thing i want to clarify, is if you opened the throtle body when doing the test to allow the fumes to flow easily "everywhere"

what has occured to me. is that the idle air bypass screw may be damaged, or unable to close far down enough. this is a mechnical point of failure which would explain why all sensors are fine... and you still get the idle too high.

i dont know if the additional air pressure from the "not leak" would be readable from the MAP sensor at idle. but definitly something worth checking. may i ask Chris to look at those values in between hes multiple data files.

given the amount of different things already tried, may be worth removing the thotle body and having a look at it in the workbench, Unfortiately your not really in a practical place to just try swapping the bosy with someone else's car to give it a test.

Hi Tuga! Once again, you chip in with help. Thank you.

• I've tried the vacuum test with both the throttle body open and closed. Especially closed as to ensure smoke went down to the IAC.

• I have thought about the idle air screw. I placed my thumb over it a couple of days ago to see if there was a leak but no change. I've screwed it all the way down and revs drop a little but not much. I've wound it back and then it seems to tighten up. I've stopped at that point for fear of damage. Worth going for it to check?

• I also disconnected the throttle cable to see if that causing an issue with the throttle not closing but no change.

• Would it be right to assume the TPS is all okay. Voltage readings are all in spec and no movement is shown.

Definitely need a new scan for a baseline. Parts have been changed since those earlier runs from a few months back. Will see what I can get done today (inbetween work)