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View Full Version : Alright, what the f*cking #$%*!!!



AforOuttie
06-03-2010, 05:58 PM
Problem: Engine has been idling rough for 3 weeks now.. Vaccum gauge used to be around 510-530 when warmed up. Now it's around 520 and dipping to 460-480 at times.

What I've checked :

Coil packs - good
Spark plugs - good
MAF - Replaced
PCV - replaced
Vaccuum/Boost Leaks - Tested, none that I can hear.

Solutions:
None so far.

I am so irritated at this point.

Any suggestions?

AforOuttie
06-03-2010, 05:59 PM
PS. when unplugging the MAF, it idles fine, Instantly. Why would the new one not work?

anger
06-03-2010, 06:07 PM
Why would the new one not work?
rebuilt maf?
change the cts..

biketsai
06-03-2010, 06:08 PM
Perhaps the new one is messed up, or the plug is messed up?

nunya
06-03-2010, 06:13 PM
TBA?

Coopa
06-03-2010, 07:13 PM
What engine code? If it's an aeb it might be your ingnition control module... just throwing things out there.

AforOuttie
06-03-2010, 07:32 PM
Its AEB engine code. The new MAF is from ECStuning, everything looked pretty good to me, even the old one still looked good. Makes sense that the new one wouldn't change anything (waste of $200).

It most likely isn't the plug, although I'm not sure how I'd check that. I have not changed the Coolant Temp Sensor, nor have I looked into the Ignition Control Module. If it makes any difference, when I go WOT on the freeway, boost still peaks around 1.6ish bar and there's no misfiring during. I'm sure a VAGCOM could easily solve this, but I don't know anyone with one, nor do I want to put down the $300 (that could be used for a part) to buy one...not just yet anyway. How would I test for the above mentioned items?

FNK
06-04-2010, 07:16 AM
Inequal compression because of gunk? Maybe an engine treathment is needed

Sales@RAI
06-04-2010, 07:31 AM
so when you unplug the MAF it idles great?

kf3506
06-04-2010, 09:26 AM
i vote ignition control module.

mikmot
06-04-2010, 09:40 AM
when unplugging the MAF makes your car run fine, then the problem is NOT your MAF, you have a massive boost/vacuum leak.
pressure test it first.

mikmot
06-04-2010, 09:43 AM
if everything checks out OK, youre going to have to get the ECU scanned.

AforOuttie
06-04-2010, 09:47 AM
so when you unplug the MAF it idles great?


Correct.

AforOuttie
06-04-2010, 09:48 AM
when unplugging the MAF makes your car run fine, then the problem is NOT your MAF, you have a massive boost/vacuum leak.
pressure test it first.

I'll check it again, but I'm pretty sure, there were no leaks that I could pick up.

AforOuttie
06-04-2010, 10:14 AM
i vote ignition control module.

Any way to check that?

AforOuttie
06-04-2010, 10:26 AM
Alright, I pressure tested it and the only leaks that I can hear are from the BOV and maybe the exhaust manifold. Whoever had the car before me installed a GFB stealth FX BOV/DV, I have it turned all the way to DV. But it seems like it's not leaking out of the "blow off area" (you know that little horn looking thing.) Rather, it feels..scratch that, it IS coming from that little crease between the main valve and the adjustment knob thing (right above the louder quieter symbol). No sure if that would cause my idling issue.
http://img.photobucket.com/albums/v308/lowtrux4life/DBOV_1pnt8T_instlld_A_Z.jpg

http://www.lltek.com/images/undahood/DBOV_1pnt8T_instlld_A_Z.jpg


And then, I can't tell for sure, but it also sounds like there might be a leak coming from the exhaust manifold to cylinder head, which is possible due to TWO of the lugs being snapped off and I haven't yet replaced them. But I'm pretty sure I've got it bolted down well enough to where the gasket should still seal it off.

Can that BOv be causing my vaccuum issue? I know a lot of you guys run just a DV, is that better for my current setup?

AforOuttie
06-04-2010, 04:48 PM
PS, is there a particular brand of DV that I might want to go with? I noticed a lot of people do the Forge 007 ones, how are they?

walky_talky20
06-04-2010, 05:53 PM
Yes, if the DV is leaking to atmosphere it can absolutely cause your idling issues. The reason for this is "false air", aka "unmetered air" entering the system. This means air is entering your engine without going through the MAF. This would cause low MAF numbers at idle, a crappy idle, and the appearance of a MAF issue.

A DV is preferable to a BOV because there is no fear of it letting in unmetered air at idle. Many of these valves don't close completely at idle. With a DV, this isn't a problem.

Forge DV is popular. My brother just got a used Forge splitter valve, it seems to be extremely high quality.

AforOuttie
06-04-2010, 07:31 PM
Yes, if the DV is leaking to atmosphere it can absolutely cause your idling issues. The reason for this is "false air", aka "unmetered air" entering the system. This means air is entering your engine without going through the MAF. This would cause low MAF numbers at idle, a crappy idle, and the appearance of a MAF issue.

A DV is preferable to a BOV because there is no fear of it letting in unmetered air at idle. Many of these valves don't close completely at idle. With a DV, this isn't a problem.

Forge DV is popular. My brother just got a used Forge splitter valve, it seems to be extremely high quality.

SweeT! I will give it a shot, thanks!

dh4life55
06-04-2010, 08:39 PM
don't go with the splitter in my opinion... i had one for a while and it was constructed nice but our cars like the air to be diverted back into the intake i just use a oem 710n diverter valve works great except been through a couple since owning my car

biketsai
06-04-2010, 08:48 PM
Maf or ICM , get a 710N

walky_talky20
06-04-2010, 10:28 PM
don't go with the splitter in my opinion... i had one for a while and it was constructed nice but our cars like the air to be diverted back into the intake i just use a oem 710n diverter valve works great except been through a couple since owning my car

True, diverter is best. I wasn't recommending the splitter, just recommending Forge based on the quality I observed in one of their products.

mikmot
06-04-2010, 10:35 PM
before you go out and spend money on a dv, if you suspect that to be an issue, remove your bov, plug the two holes, also plug your vac line going to the bov, then run the car to see if your idle stabilizes.

AforOuttie
06-06-2010, 09:46 AM
before you go out and spend money on a dv, if you suspect that to be an issue, remove your bov, plug the two holes, also plug your vac line going to the bov, then run the car to see if your idle stabilizes.

Yea, but I'm pretty sure my current BOV/DV is not supposed to be leaking like that. In fact when I first ran a pressure test for a different issue way back when, there was only a small noticeable leak through the actual valve...now this leak is pretty loud and coming from well, seems like every crease on the whole unit. I would say it needs to be fixed regardless...yea?

dh4life55
06-06-2010, 10:15 AM
yes thats something you will want to fix even if that is not your exact problem... which i dont think is causing ur problem but it could... the cts seems like a possibility though if you checked ur maf already. Im also having trouble with a rough idle what a pain

AforOuttie
06-06-2010, 10:31 AM
yes thats something you will want to fix even if that is not your exact problem... which i dont think is causing ur problem but it could... the cts seems like a possibility though if you checked ur maf already. Im also having trouble with a rough idle what a pain

Yea, I'm pretty sure the only two things that I haven't checked/replaced are the CTS and the ICM.

MkFree.B
06-07-2010, 02:48 PM
What engine code? If it's an aeb it might be your ingnition control module... just throwing things out there.

He has it. Or your actual harness to your coils. That goes out too.

AforOuttie
06-07-2010, 09:23 PM
He has it. Or your actual harness to your coils. That goes out too.

Duly noted, that will be the next thing I check after replacing the DV.