1g: Car hesitates on start up...Bad MAF?

[sliver]

My car sounds like it's about to die on start up. It happened out of the blue. Overnight.

I checked spark plugs, got spark from wires, did compression test, and so on. But when I unplugged the MAS it still had the same hesitant idle. So I don't think it's a boost leak. We are going to check for vacuum leaks and such tomorrow but overnight? IDK, help?

 

[habitatguy187]

If you don't already have a Haynes or Chiltons manual go buy one, and make sure you have a ohmeter also. You can check just about every electronic on your car with these two tools. I checked my maf just last week in about 3 minutes. Makes life a lot easier.

 

[DSM90AWD]

Check that all the sensors are connected (Coolant temp, MAS, O2..etc). May also want to reset the ECU to clear any codes. If the ECU had sensed an earlier MAS problem, your car would go into "limp" mode, making your car run very rich with low timing as to allow you to safely drive home. Reseting will clear the code, but if the MAS is still messed up, will trigger again

 

[habitatguy187]

Check that all the sensors are connected (Coolant temp, MAS, O2..etc). May also want to reset the ECU to clear any codes. If the ECU had sensed an earlier MAS problem, your car would go into "limp" mode, making your car run very rich with low timing as to allow you to safely drive home. Reseting will clear the code, but if the MAS is still messed up, will trigger again

Could you explain a little more about this "limp mode" from the ecu detecting a bad mas? Thanks

 

[dsm-onster]

If you don't think it's a boost leak then you didn't do a boost leak test. It doesn't hurt to do one. and will rule out the possibility, since this is in fact a symptom of a boost leak.

 

[sliver]

If you don't think it's a boost leak then you didn't do a boost leak test. It doesn't hurt to do one. and will rule out the possibility, since this is in fact a symptom of a boost leak.

Right, I mean I didn't get on it at all and it drove fine. Started it up and it sounds nasty. Will do blt and report back. No vacuum leaks btw.

 

[sliver]

Small leak from MBC and throttle body, fixed and problem still there. Hesitant starting then dies eventually.

 

[sliver]

How do I test the MAF?

 

[sliver]

Vacuum is reading between 12-14, then goes to 10 and dies. So this confirms a air leak right? I only found 2, one on the tb to im gasket and the other on the mbc screw. both fixed btw

 

[meliketoball]

Check or replace TB gasket if you haven't in a while, and please do boost/vacuum test it. Possibly check for a I/C pipe popping off.

 

[habitatguy187]

Vacuum is reading between 12-14, then goes to 10 and dies. So this confirms a air leak right?

No not necessarily. If your car is running very rich your vacuum will be messed up, showing in a lower vacuum than what it should be. Do you have an ohmeter? If so I'll tell you how to check your maf. Also is it hacked?

 

[sliver]

Check or replace TB gasket if you haven't in a while, and please do boost/vacuum test it. Possibly check for a I/C pipe popping off.

I've already done BLT and fixed tb gasket.

No not necessarily. If your car is running very rich your vacuum will be messed up, showing in a lower vacuum than what it should be. Do you have an ohmeter? If so I'll tell you how to check your maf. Also is it hacked?

No, my MAF is unhacked. I don't see how all of a sudden it would give out. I read other threads and they were saying o2 sensor, but that wouldn't matter on start up would it? It has to reach warm up right?

 

[habitatguy187]

May also want to reset the ECU to clear any codes. If the ECU had sensed an earlier MAS problem, your car would go into "limp" mode, making your car run very rich with low timing as to allow you to safely drive home. Reseting will clear the code, but if the MAS is still messed up, will trigger again

Have you reset your ecu yet?

 

[sliver]

yes.

I have an exhaust leak between my o2 housing and my downpipe. Also my alternator might be going out or it's just the belt a little loose. Would an exhaust leak in that area cause this?

 

[hubz91talontsi]

Is your bov recirculated?

 

[sliver]

I have an exhaust leak between my o2 housing and my downpipe. Also my alternator might be going out or it's just the belt a little loose. Would an exhaust leak in that area cause this?

?

Is your bov recirculated?

Yes, it is.

 

[habitatguy187]

I have an exhaust leak between my o2 housing and my downpipe. Also my alternator might be going out or it's just the belt a little loose. Would an exhaust leak in that area cause this?

No it wouldn't.

 

[19904g63]

same problem computer showing code 12,13 and 25 together but cant figure out whats the problem. already tried putting a different MAF but still car running lean. it dont make any difference taking the MAF plug out. somebody help!!!!!!

 

[srumel]

(OP) Sounds like something electrical. Check base timing, coil, tps, coolant temperature sensor, and condition of the ecu (leaky caps). If your battery is charging it likely isn't the alternator.

 

[fwd4g63tsi]

Ive been having the same problem as sliver.

When i bought my car i found that my maf is hacked. How do i test the maf, and when i unplug it my idle goes from 1000 to 1500 up and down. Is that normal

thank you in advance for any help.

 

[Dillonbell301]

dealing with the SAME it sounds like what I'm having right now, up hills are worse, and from complete stop. only difference is after running for awhile if i come to a stop the oil light comes on and will eventually kill the car, if i don't give it fuel.... sounds over fueled when trying to start back up and takes awhile before it will re-start. only seems to happen after its warmed up.. the hesitation and everything else is the same as above. sometimes it just runs perfect....


blt
headgasket recent
plugs wires ( the right ones gapped to .028)
oil
trans oil
took it to a recommended DSM shop where they work on them, and of course it ran perfect.....


everything checked so far as above .... coolant temp sensor next...? getting a d-link ?

 

[Nathan1993]

When I had similar problems it turned out to be a non turbo ECU in a turbo car. Not sure if this applies but I figured I would throw it out there.

 

[Dillonbell301]

When I had similar problems it turned out to be a non turbo ECU in a turbo car. Not sure if this applies but I figured I would throw it out there.

thanks, ill definitely know when i go to get my dam link put in. Mechanic said to change my CTS, I'm doing that today its only $10.

 

[richardlapalme]

Some years ago. I had this hesitation on start up, changed my isc and i put a FIAV bypass & blockoff plates on my throttle body. No problem since.

 

[Dillonbell301]

Check that all the sensors are connected (Coolant temp, MAS, O2..etc). May also want to reset the ECU to clear any codes. If the ECU had sensed an earlier MAS problem, your car would go into "limp" mode, making your car run very rich with low timing as to allow you to safely drive home. Reseting will clear the code, but if the MAS is still messed up, will trigger again

(OP) Sounds like something electrical. Check base timing, coil, tps, coolant temperature sensor, and condition of the ecu (leaky caps). If your battery is charging it likely isn't the alternator.

just bought new temp sensor.... glad i didn't just put it right in because the female is different size . Ive looked everywhere and I'm positive i know where the CTS goes and is located, has a white plastic slide for it and everything,,,the one i bought is black , everything online looks the same as what i bought ... I didn't see any that look the same as mine.... any ideas?