egr leak? rough idle and afr's
 

recently, I installed cams on the car and had a local shop tune it. the car ran fine and pulled hard for a few days. fast forward a week after i made a long 500+ mile road trip back up to school. now when i get on it, the boost builds slowly and the wastegate barely opens (boost settles to 21-ish pounds of boost [wastegate set at 25]).

at first, i thought boost leak. took apart all my piping and ic today and tightened everything up. not that.

then i thought about vacuum lines. the line under the throttle body is still intact, as is the 3/8 fitting on the top of the intake manifold. i called up a buddy and he suggested i look at all the egr hoses/fittings as well as the fuel pump regulator lines. i looked and dug around back there for a few hours and made sure everything was connected. still having issues.

when i took a pair of plyers and crimped the 3/8 hose on the top of the intake mani, the car leaned out while the rpm dropped for a second, then even out and the car cammed out like it should. when i let it up, it gets really rich for a minute, then "un-cams" itself and starts randomly camming and randomly raising the rpm. this tells me its something with that hose (egr hose? maybe?)

any ideas? any help is greatly appreciated, as my car is now slower than a stock evo :(

symptoms: idle has random hunting afr, sputters when pushing in clutch coming to a stop. wot is very rich (10.x afr) and gets a few counts of knock (judging by the flashing CEL dash light, so i cant tell you exactly how many counts).

sorry, its lengthy, but i figured i would include what i tried so we dont go in circles.

oh, forgot to add. the car cruises fine and accelerates normally. problems only arise when going to wot.

I would do a boost leak test with a compressor and some soapy water leaks always happen in the hard to tell spots.

yeah, im trying to track down someone with a compressor. only thing i can for-see being an issue is tracking down which tube it is. there are 2 distributors behind the intake manifold that you can barely get to :confused:

i guess soap will help with that a little though

Why would an egr leak cause a rich WOT? It seems like A/F would be normal with an egr leak because the air going back into the intake manifold would have already had fuel burned into it. If anything it seems like it would be lean with the extra air going into the intake manifold.

I am wondering because I am trouble shooting a problem myself. I'm having a hard time getting a straight reliable answer to this.

well im thinking that some line off the intake manifold has to have a leak.. rich at wot = not enough air = air leak. maybe not an egr line.

i bought all the stuff to do a homemade boost leak test tonight. ill do it tomorrow and report back. car drives, but its getting worse. idle is getting choppy and trying to stall on clutch depress, etc.

It would cause it to be rich be cause the air is being lost due to the positive pressure. I had a massive leak from a vacuum line that popped on the back side of the engine near the timing side. It is on the same line as the one connected to the egr, but it is not directly connected to the egr...so it did not throw a code for some reason. It was obvious during a pressure test when it all else was quiet.

To the OP what are your using for boost control?

I would check you injector latencies also.

mt057- yes, i am using a hallman mbc. i checked and chased both lines into there but found nothing. not sure what a latency is with respect to injectors, but i checked each o-ring to make sure its seated correctly and that nothing popped out.

are you on stock injectors? I had someone change my tune for me after I swapped turbos and injectors. The tuner ended up not disconnecting my battery after changeing my latencies (incorrectly) so I had a horrible idle when I did disconnected my battery and cause the computer to clear the old ones and use the new ones which were way off.

i have precision 780cc's. i dont think thats the issue, because the car ran just fine after the cams and retune (last mods i did). i made a 500+ mile road trip back up to school and next time i drove the car, it was running all sketchy like it is right now.

Do a compression check.

good call, that'll be my next step if i cant find anything with the boost leak or my bov diaphram/valve.

been trying to track down someone with a drill for the past few days (to make the boost leak tester) and its just one thing after another.. sucks not being home with access to anything other than basic hand tools :(

boost leak test revealed the throttle body seals are gone. opening and closing the tb shaft showed the seals leaking at idle, getting better, worse, better, worse, etc. as you open and close it. time for some mil-spec tb seals.

just an update on something else people could check if they have similar symptoms. pvc cap drilled out to fit a valve stem. took off the uicp and put the contraption in its place. pressurized it with a compressor and open/close the tb.

Well this is happening to mine after a egr delete. Ordered a new gasket, but if not ill get a new tv seal, this cars got 98k on it