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Old 01-13-2008, 02:06 AM   #1
Gixxer1K
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Default wrong camshaft timing or?? 2.5/2.0 hybrid

Here's the situation, 1500 miles on a 2.5/2.0 hybrid, have done oil change and gotten protuned.

Parts:

new 2.5L shortblock
2.0 heads
VF39
Gruppe-S 13.8 lb forged flywheel
800cc modified/flowed/tested wrx injectors
STI IC
Helix UP, DP
Accessport v1, protuned
Cometic head gasket - WRX stock compression ratio
Power Enterprise timing belt
  • Since the motor swap, starting cold has required cranking 15-20 seconds, then there is a hunting/unstable idle.
  • The hope was that the tune would help the starting and idle but it had no effect.
  • Initially the engine had some kind of intermittent belt/tensioner sounding noise on de-acceleration through midrange rpms. That has subsided.
  • The tuner found that the ecu was reporting knock at about 5k that limited the tune. This was with 92 octane + Torco and was very unexpected.
  • After the dyno day, I drove the car home and heard a slight diesel-sounding knock that I hadn't noticed before. It is only audible at idle and is very faint.
  • And a louder, higher pitched, shrill squeaking sound eminating from somewhere near the cams when revving through low-mid range rpms (only noticeable outside the car with the hood up).
  • I let the car cool down and started and took it for a drive a short time later and didn't hear the two sounds, perhaps the oil wasn't as heated up and so was thicker and damping the sounds?

Ideas? I'm guessing with the combination of the hard starting / hunting idle & what the tuner said, the most likely thing is the timing is off? Could the sounds be related?

Videos

weird sound - sounds somewhat like ratchet clicking on video, coming from general area driver side top of engine, occurs after hitting gas

http://wrexxor.members.winisp.net/vi...20hybrid-1.wmv

Stalls easily after tap on throttle during idling. Even worse when engine cold.
http://wrexxor.members.winisp.net/vi...20hybrid-2.wmv

Difficult to start even when warm. When cold have to crank for 15-20 seconds.

http://wrexxor.members.winisp.net/vi...20hybrid-3.wmv

Hunting idle even when warm. Worse when cold.
http://wrexxor.members.winisp.net/vi...20hybrid-4.wmv
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Old 01-13-2008, 10:12 AM   #2
BigC
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The ratcheting sound in your first video is a bit disconcerting. Get a long screwdriver and hold it up to the valve cover and put your ear to the handle. See if it's emanating from there. I had some weird sounds for the first couple thousand miles too but I don't recall hearing that.

If your concerned about timing, I would pull the covers and double check to make sure the marks are as they should be. Inspect the belt for signs of abnormal wear. For the piece of mind if nothing else...

I've messed with those modded stock injectors and had lots of trouble tuning for them. It takes a lot of diligence to get those set right. I am a novice at tuning though... I would be looking at those as at least part of your poor idle/running issue's.

Did you build the engine or? Assuming you had it on a dyno when pro-tuned, what kind of numbers were you getting?
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Old 01-13-2008, 01:19 PM   #3
R & H Garage
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what's engine vacuum?

-Dominic
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Old 01-13-2008, 01:40 PM   #4
Homemade WRX
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well both of my first questions have been asked...vacuum and timing marks...
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Old 01-13-2008, 02:42 PM   #5
Gixxer1K
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Re vacuum, do you mean at idle or? And measured with accessport?

Will check the sound with a screwdriver and under the timing belt cover.

Here is the dyno plot from a Mustang dyno.

245 power, 313 tq, and no I didn't build the engine.

Tq 313 @ 3500 which is also the boost peak before they have to start tapering from 18.5 to 10psi. Hp 245 from 4500rpm on.

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Old 01-13-2008, 03:26 PM   #6
BigC
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A boost gauge will give you a vacuum reading in HG if you have one. Good call Dominic.

As far as the screwdriver trick...that really only works well if the noise is coming from the head area. Sound won't transmit well at all through the timing cover. Not sure I'd want to be that close to the belts anyway.

If you think the sound is coming from the the timing cover area, it's is in 3 sections. The drivers side section is only held on by 3 blots and is easy to remove. You probably will have to remove the coolant overflow tank though...not hard either. The other two sections require quite a bit more effort. Was a new a new tensioner installed?

I'd rather defer to other's with more experience as far as what the numbers on that dyno sheet reveal...

Last edited by BigC; 01-13-2008 at 04:15 PM.
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Old 01-13-2008, 09:52 PM   #7
Homemade WRX
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interesting that your peak boost pressure be so far (about 1000 rpm) before your peak tq
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Old 01-13-2008, 10:41 PM   #8
sense of nature
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I'd get rid of the flywheel .Start there
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Old 01-13-2008, 10:42 PM   #9
Gixxer1K
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Update...haven't had a chance to pull the timing cover off yet. But now got a check engine light. Loaded up ecuexplorer and it says:

PO302 Cylinder 2 Misfire detected
PO304 Cylinder 4 Misfire detected
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Old 01-13-2008, 11:51 PM   #10
Cobb Tuning
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Hi Keith. My advice is to get the car back to PIA soon to have mechanical issues checked out. (see below)

I've tunes lots of hybrid 2.5 block 2.0 head WRXs. This car did indeed exhibit some very strange behaviors. No matter what the AF ratio (mid 11s to upper 10s) the ECU (02-03 WRX) would remove at least 2 degrees at exactly 5200 RPM. I spent at least 2 hours on the dyno trying to find the right combination of timing and fuel for this motor. In the end the only way i could keep the car stable was to drop the boost after torque peak. Usually tunes like this will run 17 to 19 PSI at torque peak and 14 or more at redline. The resulting power and torque are generally over 300 tq and 280 power.

This behavior is quite perplexing because i know the motor was not knocking. On select tunes i install a second knock sensor on the block and record engine noise with a high frequency data acquisition program. This software is setup to visually display the frequency spectrum of engine noise. Under these circumstances detonation is revealed as bright spot over a narrow range of frequency. This car was not detonating... but yet the ECU was removing timing, almost regardless of operating conditions at exactly the same RPM and above.

Understanding that there was likely no real knock (because of the secondary data aquizition program and knock sensor) i decided to change the stock knock sensor. My rationale was that the sensor was perhaps faulty. This change did not affect behavior of the ECU. It still pulled timing at exactly the same spot.

This behavior is certainly something unpredictable and something i could not explain. One very likely possibility is that the fuel is poor quality. To determine if fuel quality was the issue we added a full 32 oz of Torco octane booster to Keith's nearly full tank of fuel. This should have yielded a relative octane of at least 96. Given this kind of octane i should have been able to tune aggressively with little concern about the ECU pulling timing. Unfortunately, the additional octane did not really improve the performance of the car. The ECU still pulls timing at 5200 and above if the boost is allowed to taper toward 15 as opposed to 10 PSI as it is now.

So, I spent nearly 6 hours on a car that should have taken less than one total. The worst part of this is that i had to go to Keith with the answer "i don't know".

My advice to keith was to:
-Change the plugs - I'd like to know the condition of the plugs to gain insight into the local conditions of each cylinder. Perhaps one cylinder is lean
-Check the coils
A weak coil will cause major problems and will result in misfires.
-Check the CAM timing
Improper cam timing could be the culprit. A slipped tooth or two...

The shop that built the motor reports that the injectors have been cleaned and flow tested.... overall the build looks top notch and this shop has a history of high quality work.

Hopefully Keith will find some mechanical issue that is easily resolved and we can get his car up to par. I left the car "detuned" at 18 PSI tapering to 10 until he can rule out other issues.

Good Luck
Tim Bailey
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Old 01-13-2008, 11:54 PM   #11
Cobb Tuning
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Quote:
Originally Posted by Homemade WRX View Post
interesting that your peak boost pressure be so far (about 1000 rpm) before your peak tq
Look again. The peak torque and boost occur nearly simultaneously
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Old 01-13-2008, 11:55 PM   #12
Cobb Tuning
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Quote:
Originally Posted by Gixxer1K View Post
Update...haven't had a chance to pull the timing cover off yet. But now got a check engine light. Loaded up ecuexplorer and it says:

PO302 Cylinder 2 Misfire detected
PO304 Cylinder 4 Misfire detected
This could be the lightened flywheel but given the other symptoms here I can not dismiss other possible causes.
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Old 02-04-2008, 02:55 PM   #13
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Update here, the car is running pretty strong now and Steves crew has stood behind their work with troubleshooting and dyno time.

PIR has swapped the plugs with 1 step colder NGK Iridium, a grounding wire was added from the intake manif, the MAF sensor has been cleaned.

But the big discovery appears to be exhaust constriction. What they found is pulling the dyno O2 sensors out of the tailpipe boosted torque ~20 ft lb (with presumably no change to the tune)

The setup I have is a Helix catted DP, stock resonator section, a TurboXS/Magnaflow axleback. I'm a little surprised as I didn't anticpate hitting an exhaust restriction at this point. Are there any guidelines for sizing an exhaust appropriately to the power level? I notice that advertisements don't seem to include HP levels or CFM or anything like that.
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Old 02-04-2008, 04:39 PM   #14
WRX4eva
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wow, I'm glad you found the problem. Any thoughts about going w/ a bigger turbo? Also, did you do any work w/ the stock heads? Valvetrain?
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Old 02-04-2008, 05:22 PM   #15
Cobb Tuning
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Turns out your motor is simply constipated.... It needs a healthy dose of 3 inch exhaust tubing.
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Old 02-04-2008, 11:25 PM   #16
paintbing
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I Hate to hi-jack this thread, but my hybrid is throwing a CEL code P0301, P0302, P0304 and ????? on my V1AP. The CEL is NOT blinking, and I only get it about 1 of 5 times warm ups. I do have the Cobb Lightweight flywheel(Exedy). Could this be the culprit?
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Old 02-05-2008, 12:59 AM   #17
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Quote:
Originally Posted by paintbing View Post
I Hate to hi-jack this thread, but my hybrid is throwing a CEL code P0301, P0302, P0304 and ????? on my V1AP. The CEL is NOT blinking, and I only get it about 1 of 5 times warm ups. I do have the Cobb Lightweight flywheel(Exedy). Could this be the culprit?
Misfires and lightened flywheels go pretty much hand in hand from what I remember. Im not saying it happens on all cars with a lightened flywheel, but it's a common problem. Especially if the misfire is reported on all cylinders.
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Old 02-05-2008, 09:10 AM   #18
WRX4eva
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I used to get them (misfire codes) once in a while too. I believe it was from my flywheel. Is your car protuned? If so, take it back to your tuner for an inspection. Do not clear the cel codes.
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Old 02-05-2008, 11:40 AM   #19
paintbing
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My car is still on the break-in map from Cobb. Only 3 of the 4 cyl are getting the CEL code. I'm getting it Protuned a week from today from Cobb.
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Old 02-05-2008, 12:14 PM   #20
WRX4eva
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good luck and go easy on her~
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