MAP2 air temp sensor / hesitation

[apeman69]

Sorry folks, this is a bit of a long one.....

The problem
I'm trying to determine if there is anything I can do to lessen the hesitation that my car has when moving off from idling.
On pressing the accelerator from standstill there is a quite noticable momentary pause before the car actually moves.
I have previously been told that this can be because it takes longer for the air to get to the MAP sensor than it did to get to the MAF and also that it could be down to a presence in overlapping cells in one of the MAP2 tables.
When the MAP2 was installed I assumed there would be some drivability/performance trade off but TBH I was, and still am, quite appalled at the kangaroo effect the car displays.
In general driving when I stop, the idling speed will very often reduce to 500rpm or below for a fraction of a second. Once or twice the car has even stalled because of this.

What I have thought about
Is there a 'best place' for the MAP2 air temp sensor?
Where's yours?
Mine is dangling inside the airbox (not affixed to anything apart from it's wiring).
I'm guessing that an air temp sensor that is affixed to something would work better than one that is dangling and potentially waggling about... or would it make any difference considering it's in the small space of the standard airbox?
I've seen a member's car with the AIT sensor screwed into the battery side of the snorkel and his car does not hesitate anything like mine does. This is the only reason why I am querying placement of the sensor.

I am going to have a look at the R2D2 BOV I have on there and play with the spring to ensure it is set up correctly, in order to eliminate this. However, I did not have any BOV-related problems before the MAP2 was installed.

I attempted to clean the idle control valve but, after removing all sorts of gubbins to get at it, found the thing to be screwed in rather than bolted and I didn't fancy dropping the screws in the engine bay somewhere. I know that this will get dirty over time but, again, I did not have any idling/hesitation problems before the MAP2 was installed. I was just going to do this to eliminate it from my enquiries.

Other things to consider
I have 530cc injectors. Could this have any bearing?
I have grade 7 iridium plugs.
From cold starts I feel that the car is terrible unless it is left to run for a minute or so. It stutters more than Gareth Gates in a job interview. I have previously just put this down to having a colder grade of plug.
There are no other noticable running problems, just the transition from idling to under load.
The enrichment settings on the MAP2 have been tweaked and tweaked and tweaked again (by three individuals who all know what they're doing) but to no avail.
The MAF has been 'removed' in a functional sense though it's gutted casing (which still forms part of the air intake) is still there attached to the airbox and snorkel.
There may be something pertinent within my signature that I haven't mentioned.

Any thoughts or comments would be welcomed because I need to do something to get this improved. Please don't just say "move the sensor and find out" or similar because I don't want to go drilling holes in stuff only to find no improvement.
Thanks everyone

[mike74]

i don't spose you've checked the TPS have you? it might be that that's needing adjusted or replaced? i had the exact same symptoms on my pulsar when i had to disconnect the TPS to reset the timing. you'd press the throttle & there was literally a second delay before the engine revved. just a thought but you never know...
hope you get it sorted anyway

[AlanDITD]

Hi Apeman,

Im not sure on the hesitating, but you can rule out the grade 7 plugs on idle..i have ran these i know other people have and do not have any stuttering on startup.

Are you running an aftermarket FPR?

Also ojn the dyno graphs there must be a dip in power? nothing show up on there? odd AFR's ect?

[swinks]

What air filter you are running at the moment? I've noticed similar issue (maybe not such as) with forced induction filter CDA. Car was idling 550 ish, and afr was noticeably leaner. And as you saying, reaction time on acceleration pedal was 1 - 2 secs slower, but then car was pulling very hard (fast), same with gear changes, barely noticeable longer changes. But saying that it was with MAF inside.

[Gowf]

Unfortunately with the way the MAP2 works by giving false signals to the ECU in the form of KVFs then you will always have the issue if nothing is done with the transient fuel map. The main issue with the MAP2 is that you have very little controlibility of this, given only a TPS and MAP enrichment table.

Putting the bigger injectors in will make this worse, as you are telling the ECU there is a lot less airflow than there actualy is.

With regards to the lower idle, you can up it with the idle screw I set mine to about 1k as it was the only place i could get sensible AFR at idle.

The main downside is the cold enrichment. As your saying, when cold the car will have issues with driving. This is because the standard temperature enrichment tables will not take into account you have bigger injectors in there, and as your showing it less air flow, you find that you run quite lean. Mine, albeit flow a lot more air, was terrible unless you warmed it up, feels like spark blow out.

So all this being said, how much are the MAP and TPS enrichment tables at now? I would recomend upping your idle a wee bit when the car has been allowed to warm up. It really did help mine.

[apeman69]

i don't spose you've checked the TPS have you?
No but thanks, I'll bear it in mind.



...you can rule out the grade 7 plugs on idle..i have ran these i know other people have and do not have any stuttering on startup.
Are you running an aftermarket FPR?
Also ojn the dyno graphs there must be a dip in power? nothing show up on there? odd AFR's ect?
Cheers, SARD AFPR is on there and nothing strange on the dyno prints.



What air filter you are running at the moment?
Ralliart panel filter in factory airbox connected to factory snorkel. The body of the MAF is there but the innards have been removed.



how much are the MAP and TPS enrichment tables at now? I would recomend upping your idle a wee bit when the car has been allowed to warm up.
Increasing the idling speed is something I CAN do and was on my list of "This has got to help: quick fixes" so I'll do that in the meantime.
I've attached screen prints of the MAP2 ECU configuration screens for the primary and secondary maps.

[Gowf]

Alan, its been a while since ive looked at the software so thanks for posting that up. It is as i thought, that the enrichment only comes in from 1000rpm, so below that it is 35% ( i dont think that it interpolates from 1000-0rpm). And also as you are running such low KVF below 1000rpm due to the larger injectors the 35% enrichment may not be enough to arbitrarily enrich the fuel to compensate for the lag in air flow, if that makes sense. Try turning your idle up a bit. Also, could you post a screen shot of your primary fuel map?

[apeman69]

So should I be aiming for an idle of 1000rpm, a bit lower or a bit higher. I'm not overly concerned what the actual idling speed is on a daily basis (regarding fuel consumption etc) as long as it doesn't negatively affect drivability, which I assume in this case it could only benefit.
Primary fuel map below. I hope it's readable!
On-line tuning services anyone? /lol

[Gowf]

Just wanted to have a look at the bottom 2 lines. The ECU doesnt like anything below 17Hz, and I was wondering how much fueling there was below 1k. Looks totaly fine though, so id up your idle and see how that effects it. What you may then find is you need to lower the value of the enrichment, but prob unlikely.

Like i say, give it a go and let me know what the result is

[apeman69]

So, while I consider taking a screwdriver to my idle speed adjustment screw:-
Is there a 'best place' for the MAP2 air temp sensor? It would seem logical to stick it in the airbox as it's the most easily accessible place close to the inlet. Would there be much benefit in moving it closer to the throttle body (inlet elbow perhaps). I'm thinking about the best place in terms of getting an accurate temp reading that the ECU would appreciate. Would there be any benefit or am I wasting everyone's time even thinking about it? Any thoughts?
Where's yours everybody?

[Gowf]

Basicaly the AIT does change your fueling according to the temp of the air, if its colder it adds more fuel etc.

However, it assumes that you cannot get more than 100% efficiency from your intercooler so if you have it in the ambient air stream it is totaly fine. If you have it in the inlet elbow, ie so it can see boost, it will fuel for the increased temperature that you have in there (due to the inefficiencies in the intercooler) and thus you may underfuel as the car was mapped using ambient temp as a guide.

TBH it will make pretty much no difference at all to the prob that your having.

[apeman69]

I didn't think it would make any difference to my symptoms. Just wondered where people put them as I've seen one in the snorkel and heard a whisper that someone may try putting it in the intercooler piping somewhere. Presumably wherever it is, to a degree, the car can be mapped taking into account the relative readings it would be supplying. :uhoh2:
I was just wondering about the effects of this and that, really, in my quest to actually learn something for a change. :embarasse

Anyway Gareth, 1000rpm, lower or higher as a recommended starting point or should I just play it by screwdriver?

[apeman69]

I'm about to have a go at increasing the idle speed.
I have seen from EvoScan logs that there is a 'Target Idle Speed' in the ECU.
This is how I intend to adjust the idle speed:-
Run the car until normal operating temp is reached.
Run EvoScan on the carPC and connect to the ECU so it is in diagnostic mode. I read somewhere that this will stop the idle control valve relearning the idle speed, presumably learning from the ECU parameter.
Run MAP-CAL2 on the laptop (in the engine bay) and connect to the MAP2 so I can see what the idle speed is during adjustment.
Turn the idle screw until the desired speed is achieved.

My question is: as the ECU has a target idle speed will the idle control valve ever attempt to reset to the 650rpm or whatever target of the engine ECU?
If so then under what circumstances would this occur? ECU reset from flat battery or battery disconnect for examples?
If the ICV does ever reset the idle speed then the screw I will have adjusted will then be in the wrong position and, considering I will be undoing the screw to increase the idle speed then wouldn't this eventually be no longer adjustable should this procedure need to be done on a regular basis? This may seem to be overkill in terms of the number of ECU resets required however, I travel abroad at least twice per year and invariably have a flat battery on my return.

[Gowf]

It shouldnt reset. With regards to the ECU target idle, i just turned mine up manualy, and it never tried to lower it. Now others will no more on the ins and outs of this, but i assume its similar to fuel trims, it bases its change on the original value, so if this value is changed it will only trim it the specified amount that was originaly set. If that makes sense?

[apeman69]

I've just increased the idle speed to around 900 when in neutral/park.
When in gear the RPM drops to a more healthy (compared to previously) 700-750.
I took the car on a 10 minute drive around the neighbourhood and the change to the pick up of the car from standstill is quite phenomenal. I was also getting a bit of a lull in RPMs in between gear changes when using light throttle which translated into not very smooth forward movement. On the short test drive this has also improved dramatically.
Previously it was idling at around 650 in neutral, dropping to 500 and often lower when in gear, which I've known for a long time was simply too low.
I'll give it a few days of 'proper' driving and see what effect this has had. At the moment it's good and I'm quite pleased.
Thanks Gowf and all.

[Wodjno]

I've just increased the idle speed to around 900 when in neutral/park.
When in gear the RPM drops to a more healthy (compared to previously) 700-750.
I took the car on a 10 minute drive around the neighbourhood and the change to the pick up of the car from standstill is quite phenomenal. I was also getting a bit of a lull in RPMs in between gear changes when using light throttle which translated into not very smooth forward movement. On the short test drive this has also improved dramatically.
Previously it was idling at around 650 in neutral, dropping to 500 and often lower when in gear, which I've known for a long time was simply too low.
I'll give it a few days of 'proper' driving and see what effect this has had. At the moment it's good and I'm quite pleased.
Thanks Gowf and all.

/Hmmm Interesting /yes

So has this Enriched the AFR at idle ? Or just raised the RPM ?

[Gowf]

Its raised the idle, but as the transient fuel tables only have resolution from 1000rpm the lean tip will be far more predominant below that

[apeman69]

the lean tip will be far more predominant below that
I know you're Scottish but what does that mean exactly in English? :uhoh:
AFR according to MAP-CAL was 14.5 I think, but didn't really pay much attention to it. As I don't have wideband fitted would this (14.5) be relevant anyway?

[Gowf]

If there's no wideband then the mapcal dashboard figure is just some random value, dont worry about it.

Its just what i said earlier. The lean tip is the hesitation you feel whn you initialy press the throttle, due to the initial moment of running lean (as youve let more air in) before the ecu can react (because it doesnt have a MAF). So to rectify this, when sudden changes in MAP or TPS are obversed by the MAP2 it fires in some amount of fuel. This is controlled by a table, but as it only starts at 1000rpm, it doesnt interpolate below that so you dont really have any true control over it below that. So the nearer to 1000rpm you are at idle, the better it will feel

[Wodjno]

I know you're Scottish but what does that mean exactly in English? :uhoh:
AFR according to MAP-CAL was 14.5 I think, but didn't really pay much attention to it. As I don't have wideband fitted would this (14.5) be relevant anyway?

How are you tuning a Map2 without Wideband :dizzy2:

[Gowf]

He's not, he's had it mapped by others

[apeman69]

I'm not tuning the MAP2, I've increased the idling speed by use of my almighty screwdriver.:smash: Hence why I questioned whether the AFR reading provided by MAP-CAL would be of any use.

[Wodjno]

I'm not tuning the MAP2, I've increased the idling speed by use of my almighty screwdriver.:smash: Hence why I questioned whether the AFR reading provided by MAP-CAL would be of any use.:2thumbsup :2thumbsup :2thumbsup :2thumbsup :2thumbsup

The Screwdriver is Mightier than the Laptop :iagree:

[Gowf]

Just to add though Alan, upping the idle, will only bring the revs up, so you will be in a different cell in the fuel table but that will be set with an afr of 14.7. All the no/low load cells are for the purpose of Mr MOT man

[apeman69]

And Mr MOT man wasn't too happy this year... emissions close to limit, allegedly :deal2:

[Gowf]

They are a nightmare to get through, you really do need to roast them to get the cat to its light off temp. It took me an hour when i did Mats sitting on the gas analyser to get it through the retest. Mr MOT man didnt like that, but tough that will teach him for not putting it through the correct test. Its not a 6A13 engine!

[apeman69]

If I got my cat up to temp then I'd have no interior left. :dalek:
It was wrapped in a plastic bag on the back seat! :chugchug:

[apeman69]

Just got home from work (7 miles each way, around town and dual carriageways). I'd forgotten how pleasurable it is to drive these cars. I'm more than pleased with the result of simply increasing the idling speed.
Also just added a fuel up on fuelly and 20.3 mpg is about what I expected from a 170 mile 80-100mph motorway run and 100 miles around town, some of which was giving the car a bit of a pasting. I even managed to get the ASC light to illuminate while accelerating out of a roundabout. Until now I didn't even know it did light up whilst driving!
Gone are the 30 mpg days of no boost and no throttle!

[Turbo_Steve]

You can get 30mpg if you could get it before. Just need a better ECU.

[apeman69]

You can get 30mpg if you could get it before. Just need a better ECU.
That was driving like a grand father. I don't want 30 mpg anymore :)

[Eurospec]

Might be worth a check to see if your O2 sensor is working, but yeah, thats not an unusual mileage with bigger injectors/map2.

The idle speed trick does work, as gareth says, its the transient response below 1000rpm combined with the fact that you are telling the stock ecu that the air is at the air flow meter, whereas actually its already in the plenum.

Cheers,

Ben

[ILLEGAL]

this is a great read.. it answers alot of my question about what i was feeling with my mapecu2 upon throttle.. once my mapecu2 has self learnt a map ill raise the idle too 1000rpms, and try that.. wish i didnt delete my old map now!

i tried alot of things! a new iidle control valve. blow off valve. fuel pump, injectors, standard ecu.. lol never thought that it was just the fact the mapecu didnt have control under 1000rpm!


so im guessing it 100% now mate?

[apeman69]

I'm idling at about 925 when warm and in neutral and I'd say it's about 90% how I'd like it. It's a thousand times more drivable now though!
After a long run or stopping from a heavy blast the rpms drop a little lower than when idling in gear (around 700 in gear) and there can be a slight hesitation under these conditions but this could be the idle control valve which I haven't cleaned or just because of my setup with the bigger injectors. Increasing the idle speed a touch more is on my mental list of things to do whilst I decide whether to get a standalone.
Try it 'cos it does work well.
BTW Ben, my lambda sensor is working as expected, as I found out yesterday. My new wideband setup isn't functioning correctly but that's another story!