Mysterious Engine Trouble...knocking and power loss.

Boostd4 · Jul 9, 2009, 10:54 AM

Just to start off, my car started off as a strong car...doing 305whp/305wtq on GST Motorsport's Mustang Dyno with just a cat back and a panel filter.

About 2 months ago I decided to do a turbo upgrade as well as the mods to support it. I started with a Garrett 3076R, then switched to a Dom2.

On to the problem, the car has a global loss of power throughout the powerband and is knocking badly above 6K rpm. The car lost power even before the knock...so the engine knock isn't the only point where power was lost. When you overlay the dyno graphs (stock turbo vs. upgraded turbo) there is a linear loss across the entire power band. The AFRs are solid at 10.8 throughout and the logs are showing that boost is consistent as well...the car simply is making less power. The guys at the shop even replaced all of the parts that were upgraded (basically returned the car to stock) and still experienced the same issue. Just to be clear, the engine knock isn't the issue...rather it is a side effect of the entire power loss issue.

I've listed my mods, tests performed, and other relevant info below. I'm really looking for suggestions as to what could possibly be a possible solution for this problem. Hopefully you guys have some ideas. I've ruled out most of the mechanical possibilities...so now I'm weeding out possible electrical issues. The car is being tuned by Bryan@GST...so before the question is raised...it's not the tuner.

I will monitor the thread closely, so if you have questions about the car other than what I've listed I'll provide any information that I can.

There are other owners having similar issues on very close to stock cars...so I'm hoping this isn't a huge issue with the car. I haven't been able to find anyone that has had a solution to this issue on any EvoX board. Hopefully if someone else is having this issue this thread will help find the solution.

Current mods:

Nisei Full IC pipe kit w/intake
K&N Cone filter (closed top)
AMS FMIC
AMS DP
Test pipe
GReddy TiC Cat-Back
FIC 950cc Injectors
Blouch Dominator 2
Forge WGA
GST Boost Pill

Tests Performed:

3 Boost leak tests
3 separate Compression tests (150psi across the board each test)
3 leak down tests (no issues)
All 4 cylinders boroscoped, no signs of piston or cylinder wall damage
No CELs
New spark plugs installed (originals were fine)

Other info:

Battery was disconnected during turbo install and went directly back on the dyno...no re-learn performed. Possible issue?

MAF Sensor was accidentally dropped on the ground during filter install...but no CELs and AFRs are consistent.

With the exception of the turbo and the injectors...the longblock is untouched.

tonyboy · Jul 9, 2009, 11:23 AM

is the knock audible? If not maybe a faulty knock sensor? because you've done the necessary tests...i mean leak down and compression...all i can think of is the knock sensor...have you tried replacing or borrowed a working knock sensor? keep us posted...

Boostd4 · Jul 9, 2009, 11:27 AM

Quote:

Originally Posted by tonyboy

is the knock audible? If not maybe a faulty knock sensor? because you've done the necessary tests...i mean leak down and compression...all i can think of is the knock sensor...have you tried replacing or borrowed a working knock sensor? keep us posted...

Yes, it's audible on the dyno. Bryan also captured it on Evoscan during the dyno runs. We thought it might have been some phantom knock...but after a few runs it was easy to hear it. Now that the blocks are aluminum it's much easier to detect by ear.

dkstas · Jul 9, 2009, 12:25 PM

^I had similar symptoms with my set-up (Dom. 2, DW 800cc inj.) . My car would break up after 5K causng 5-6 counts of knock. After I changed my spark-plugs it cleared up (wasn't their a thread on bad spark plugs from the factory?), and the car definately feels better.

tsitalon1 · Jul 9, 2009, 12:25 PM

Maybe I missed it, but were the turbo blades inspected for damage...maybe something broke off the dropped maf sensor and was ingested.

Any change in IAT before after issue started?

Boostd4 · Jul 9, 2009, 12:33 PM

Quote:

Originally Posted by tsitalon1

Maybe I missed it, but were the turbo blades inspected for damage...maybe something broke off the dropped maf sensor and was ingested.

Any change in IAT before after issue started?

MAF was dropped before the Dom2 was put on...so probably not an issue.

IATs were normal.

Boostd4 · Jul 9, 2009, 12:34 PM

Quote:

Originally Posted by dkstas

^I had similar symptoms with my set-up (Dom. 2, DW 800cc inj.) . My car would break up after 5K causng 5-6 counts of knock. After I changed my spark-plugs it cleared up (wasn't their a thread on bad spark plugs from the factory?), and the car definately feels better.

Well, we swapped in a fresh set of plugs and it didn't seem to help...my thoughts were maybe the coil packs? But I'm assuming that if something was up with the coils we'd see that by the AFR fluctuating or misfiring throughout the powerband. I was also thinking that IF the coilpacks were going...maybe the problem only existed in certain parts of the RPM range.

Hiboost · Jul 9, 2009, 12:39 PM

So are we talking 1-3 knock sum or like 10+ here?

Somehow I had a feeling that ditching the Garret Gt3076R turbo wasn't going to fix your knock issues.

I feel bad that you are having all these issues with your Evo X when it was a strong runner before you performed major mods like a turbo upgrade. So if you are getting knock is it possible that your injectors aren't delivering the fuel evenly? Was the car tuned on the injectors before the turbo swaps and if not can you swap back to the stock injectors and see if there is any difference? I still think a good fuel pump is worth getting installed sooner than later, even if your AFR's are rich and safe now. Once you resolve these issues you will be limited to lower boost or risk leaning out without control down the road.

If compression is the same across all 4 and air entering the engine is even, fuel delivery seems to be the only other variable that could cause knock. You might be 10.3 AFR's in 3 cylinders and 12.5 AFR in another for a combined 10.8 on your wide band which is reading the average from all 4 cylinders downstream of the turbo. I know if all the plugs seem evenly colored with no signs of detonation that possibility seems remote but you literally have to do a WOT run and turn off the engine within 30 seconds in order to read the plugs accurately.

With the bigger turbos the spark plug gap can't be too large or it will blow out at higher boost. Likely this isn't your issue though but something to keep in mind as I had hesitation with zero related knock from having gaps too wide. Perhaps your ignition coils need a looking at, but I'm not sure if a lack of spark would cause knock.

Possibly the timing chain on the cams is off a tooth?

I'll let others comment further on what else it could be but those are a few things I could think of off the bat that aren't directly tuning related. Hopefully you'll get this sorted out soon!

dkstas · Jul 9, 2009, 12:43 PM

When the car would break up, my AFR's would drop deep in ton the 9's. You probably have a different problem considering your AFR's are consistant.

Boostd4 · Jul 9, 2009, 12:47 PM

Quote:

Originally Posted by Hiboost

So are we talking 1-3 knock sum or like 10+ here?

Somehow I had a feeling that ditching the Garret Gt3076R turbo wasn't going to fix your knock issues.

I feel bad that you are having all these issues with your Evo X when it was a strong runner before you performed major mods like a turbo upgrade. So if you are getting knock is it possible that your injectors aren't delivering the fuel evenly? Was the car tuned on the injectors before the turbo swaps and if not can you swap back to the stock injectors and see if there is any difference? I still think a good fuel pump is worth getting installed sooner than later, even if your AFR's are rich and safe now. Once you resolve these issues you will be limited to lower boost or risk leaning out without control down the road.

If compression is the same across all 4 and air entering the engine is even, fuel delivery seems to be the only other variable that could cause knock. You might be 10.3 AFR's in 3 cylinders and 12.5 AFR in another for a combined 10.8 on your wide band which is reading the average from all 4 cylinders downstream of the turbo. I know if all the plugs seem evenly colored with no signs of detonation that possibility seems remote but you literally have to do a WOT run and turn off the engine within 30 seconds in order to read the plugs accurately.

With the bigger turbos the spark plug gap can't be too large or it will blow out at higher boost. Likely this isn't your issue though but something to keep in mind as I had hesitation with zero related knock from having gaps too wide. Perhaps your ignition coils need a looking at, but I'm not sure if a lack of spark would cause knock.

Possibly the timing chain on the cams is off a tooth?

I'll let others comment further on what else it could be but those are a few things I could think of off the bat that aren't directly tuning related. Hopefully you'll get this sorted out soon!

I think my time with the Garrett may have made a small issue come to light as a bigger one

.

We put the stock injectors in just for giggles as we were thinking maybe the scenario you described was happening...no change. Still very uniform in the power loss and symptoms.

Not so sure about the timing chain...we never cracked open the valve cover...so unless something broke probably not a possibility.

I do have a fuel pump to swap in as soon as my install kit arrives...so I'll be popping that in soon.

Pretty much at our wits end over here. I've gotten great input from you before, so I definitely appreciate your advice.

tonyboy · Jul 9, 2009, 01:00 PM

have you tried changing or swapping with a another stock coils to your evo x? just to test it out...man i hope everything would get fixed for ya...after that garret issue and now this...good luck man...

Boostd4 · Jul 9, 2009, 01:02 PM

Quote:

Originally Posted by tonyboy

have you tried changing or swapping with a another stock coils to your evo x? just to test it out...man i hope everything would get fixed for ya...after that garret issue and now this...good luck man...

That's the next step, going to borrow a set from a local...hopefully that puts us in the right direction.

tsitalon1 · Jul 9, 2009, 01:08 PM

Could this be a case of a bad tank of gas or gas station? I know it seems trivial, but I don't think you mentioned changing gas stations or adding any c16 to see what happens to the knock.

tonyboy · Jul 9, 2009, 01:09 PM

^^ +1 good test too..

Boostd4 · Jul 9, 2009, 01:13 PM

Quote:

Originally Posted by tsitalon1

Could this be a case of a bad tank of gas or gas station? I know it seems trivial, but I don't think you mentioned changing gas stations or adding any c16 to see what happens to the knock.

Yeah, forgot to add that part above. We went through about 3 tanks of gas. 2 from my normal 76 station and one from a different station...same results.

I think the next time we put it on the dyno we're going to splash a little 100 octane in there to see what it does.