Soonto_HAS_soop Posted February 16, 2006 Share Posted February 16, 2006 Right, does anyone know what the voltage should be from the MAP sensor when the car is at operating temps and idling? Should it then be a straight increase in voltage when you increase the throttle? It shouldn't drop voltage then increase after should it? What could make it run higher than it should do at idle? Link to comment Share on other sites More sharing options...
eyefi Posted February 16, 2006 Share Posted February 16, 2006 MAP sensor measures the manifold pressure so no it won't be a straight rise when you apply throttle. if you blip the throttle with no load it will rise, drop to lower, then slightly rise back up to settle at it's idle. mine reads 1.146v at idle but thats with non stock cams (which will have an effect) Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 Well I have currently got HKS 264's, and mine is deciding to idle at 1.66v. When throttle is applied as a constant rising level, it drops to between 1.2-1.4v and then begins to raise again to 1.6v+. If I blip the throttle, it drops, then rises, drops again and then rises to the idle level (if you understand what I mean?). I think it might be this that is causing my ultra rich idle. I'm wondering if I have a dodgy MAP sensor, or could something else cause it to feck about at idle? Link to comment Share on other sites More sharing options...
Ian C Posted February 16, 2006 Share Posted February 16, 2006 I don't think your MAP sensor is bad, you must have a boost gauge surely, what vacuum does that read at idle? 1.66v on the stock MAP sensor is -0.52kg/cm2, so if your gauge shows that then it's reading correctly. I get -0.60 to -0.61 at idle, 1000rpm with 256in 264ex cams, so your idle may be pulling in a little too much air. Pardon me if I've missed a thread but how do you know it's overfuelling? When you crack the throttle open does it chug and start to die? What other mods have you got - fuelling and electronics related... -Ian Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 I don't think your MAP sensor is bad, you must have a boost gauge surely, what vacuum does that read at idle? 1.66v on the stock MAP sensor is -0.52kg/cm2, so if your gauge shows that then it's reading correctly. I get -0.60 to -0.61 at idle, 1000rpm with 256in 264ex cams, so your idle may be pulling in a little too much air. Pardon me if I've missed a thread but how do you know it's overfuelling? When you crack the throttle open does it chug and start to die? What other mods have you got - fuelling and electronics related... -Ian The wideband tells me that I am running rich at idle 9.8-10.8 at operating temperature (85-90 degree C water temp), that's after a full free air calibration. When I open the throttle, it doesn't chug and start to die, but then it doesn't go over 11.0 on the wideband. And the wideband was checked against an MOT stations gas analyser. If 1.66v on the MAP sensor (is there a link to that information per chance) is 0.52kg/cm2, then why would the voltage DROP when throttle is applied? I would of thought if idle was 1.66, then applying an evenly increasing throttle would see it rise from 1.66v up. Why would it go 1.66 to 1.2 to 1.66+, then operate as normal? Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 Is the MAP sensor not supposed to work like the attached "correct?" line, whereas mine is doing the "now" line? Is this not completely wrong??map sensor.xls Link to comment Share on other sites More sharing options...
eyefi Posted February 16, 2006 Share Posted February 16, 2006 mine reads 1.146v at idle but thats with non stock cams (which will have an effect) and also a non stock map sensor, so it is no comparison whatsoever. Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 and also a non stock map sensor, so it is no comparison whatsoever. Is that a Greddy MAP sensor per chance. Link to comment Share on other sites More sharing options...
TLicense Posted February 16, 2006 Share Posted February 16, 2006 Is the MAP sensor not supposed to work like the attached "correct?" line, No, well maybe it depends at what boost/vacuum you've got at those RPM. whereas mine is doing the "now" line? Is this not completely wrong?? A MAP sensor's voltage will rise as boost does. Is it the stock MAP sensor you've got? Link to comment Share on other sites More sharing options...
eyefi Posted February 16, 2006 Share Posted February 16, 2006 Is that a Greddy MAP sensor per chance. nah, apexi, which is a denso unit. Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 No, well maybe it depends at what boost/vacuum you've got at those RPM. A MAP sensor's voltage will rise as boost does. Is it the stock MAP sensor you've got? Edited to show the boost pressures at the time of the issues. I still have the standard MAP sensor.map sensor.xls Link to comment Share on other sites More sharing options...
TLicense Posted February 16, 2006 Share Posted February 16, 2006 Not sure about the actual values but the slope of the graph (The pink one) looks right compared to the boost. Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 Not sure about the actual values but the slope of the graph (The pink one) looks right compared to the boost. So, if my car is doing the dark blue line, what could be making it do this? Could the idle valve on the back of the inlet manifold be stuck/faulty, and be telling the ECU that it is wide open? I have a spare of these, should I try and change it over to check it? Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 Anyone else? I have just fitted 680cc injectors and have been using the global correction facility on my emanage to move the car up and down my driveway. Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted February 16, 2006 Share Posted February 16, 2006 I have always found that the injector correction feature quite good on the emanage, you can always tweak the % change to get the fuelling closer, as for you other problem i encountered a similar problem when i changed over to Apex Power FC with higher lift cams! the thing i find odd about your problem is the your boost/vacume is not showing the odd drop your getting! from idle you open the throttle the engine takes more air, but what usually happens is you get more vacume before the airflow catches up, so you see a dip in the map sensor voltage and then it rises again, this is quite often the case when installing high lift cams, as they demand more air so the fuelling needs to be tweaked or you get an unsteady idle! Your AFR seems well out can't understand why the ECU is not pulling the fuelling back to stoic? unless you have to much fuel correction dialed in and the ECU cannot cope! Link to comment Share on other sites More sharing options...
TLicense Posted February 16, 2006 Share Posted February 16, 2006 So, if my car is doing the dark blue line, what could be making it do this? Could the idle valve on the back of the inlet manifold be stuck/faulty, and be telling the ECU that it is wide open? I have a spare of these, should I try and change it over to check it? If the voltage from the MAP sensor is dropping when you are increasing in boost then their is something wrong with the sensor. No two ways about it. Are you definitely sure this is what is happening? Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 If the voltage from the MAP sensor is dropping when you are increasing in boost then their is something wrong with the sensor. No two ways about it. Are you definitely sure this is what is happening? I will triple check tonight once I get home from work. Anyone got a spare MAP sensor kicking around at all?? Link to comment Share on other sites More sharing options...
TLicense Posted February 16, 2006 Share Posted February 16, 2006 As it happens... I can send you mine, if it gets rid of your problem I'll need yours by return of post (Otherwise I'll have a big hole in my intake!- I have an AEM 3.5 Bar sensor, but it's in a different location) Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 16, 2006 Author Share Posted February 16, 2006 As it happens... I can send you mine, if it gets rid of your problem I'll need yours by return of post (Otherwise I'll have a big hole in my intake!- I have an AEM 3.5 Bar sensor, but it's in a different location) Thanks for the offer Tony, but what hole will you have left in your intake? It bolts to the outside and is fed by a small pipe? How do you want to go about doing this? Link to comment Share on other sites More sharing options...
TLicense Posted February 16, 2006 Share Posted February 16, 2006 Fair enough then, pm me your address and I'll pop it in the post! Link to comment Share on other sites More sharing options...
TLicense Posted February 16, 2006 Share Posted February 16, 2006 I'll take it off over the weekend, hopefully I'll be able to get it to you for Monday. Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 17, 2006 Author Share Posted February 17, 2006 I'll take it off over the weekend, hopefully I'll be able to get it to you for Monday. Thanks a lot Tony, really appreciate it mate. Link to comment Share on other sites More sharing options...
secondjump Posted February 17, 2006 Share Posted February 17, 2006 Ben, have you considered purchasing a map off/or getting your car mapped by Ian C? Best money I spent during my single conversion. Car runs with almost stock like smoothness, and excellent after service when tweaks are required. Link to comment Share on other sites More sharing options...
Soonto_HAS_soop Posted February 17, 2006 Author Share Posted February 17, 2006 For what I have done I can do the map myself (I am only using the global correction to get started), but this is on idle, the ECU takes over. I am getting varying levels of over rich condition when the car is idling and warm, so it is something else giving spurious readings, without actually kicking up any fault codes. I removed the MAP sensor last night and had a quick look at it, plumbed it back in, and I got an AFR reading of 8.5 at warm idle!! , I then removed it and blew and sucked on the nipple (shit that sounds bad) replaced it and it ran at 12.7 warm idle. It must be the MAP sensor that is fooked. Ben, have you considered purchasing a map off/or getting your car mapped by Ian C? Best money I spent during my single conversion. Car runs with almost stock like smoothness, and excellent after service when tweaks are required. Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now