I've been dealing with a poor performing engine in my EVO and it seems to be due to a lot of knock and the subsequent timing pull back by the ECU.
Al did a custom Dynoflash to my car and found lots of knock which we attributed to bad fuel and he had to detune the stock maps somewhat to make the car run better. I've since changed to the best gas I can find...
Since then I've gone with AEM EMS standalone and George from boost solutions installed and tuned it. He also said that my car "just does not like timing"
The Knock sensor appears to be working well since these conditions were detected with independent knock sensors than the stock unit.
Anyway, I'm fairly pissed about this since it's a undesireable condition from a performance or safety standpoint. I wonder how many people have similar experiences and what if anythingh can be done to correct this.
Also, I invite all the cognoscenti to explain what can cause this particular problem. BTW, I use the 93 octane Amoco Ultimate which other guys use as well and they don't have this problem either.
Please help!!

 

how can you tell? I have a data logger and I was wondering what you would see if you have knock?

 

I don't know what other mods you already have on the car.. But I discovered my car had unusually high injector duty cycles, and it was still running a little lean.. (stock injectors and pump at the time) Honestly, if you haven't already done it, it may be a "bad performing" pump or an issue with the injectors.. I did replace my plugs with colder ones and it seemed to help for a while.

I can only assume you've been down that road already and are still having those issues though.

 

You can't directly see knock with the data logger, however under load, if your loggind data, you may see sudden timing changes at certain RPM's where the curve might otherwise be smooth..

 

During the street tune that Al did first, he could see the knock in his knock linlk as well as seeing the severe timing pull back from the 3rd gear run data logs.
The second time around, George was installing and tuning the AEM ems that I've got and he said "your car does not like timing"... I don't know how he made that determination, but I presume he saw datalogs and possibly real time knock displays of some kind. The AEM ems, will datalog all kinds of things including knock sensor voltages.

 

Well, I did what I thought was indicated. After Al's Dynoflash, I did the following:
1 fuel pump
2 fuel rail (Perrin)
3 660 RC injectors
4 HKS suction kit
5 B&B downpipe & test pipe
6 AEM ems

According to George, I still have these issues of knock caused by timing advance. I presume he knows what he is doing and he's tuned the car with all the above mods taken into account. Especially since he installed them all
It's a vexing problem for sure.......

 

I had the same problem on my car with the EMS and my pump gas tune from AMS in Chicago. We attributed it to bad gas, but we still were able to pull 350hp to the wheels on 93 but my timing was more conservative than the stock ecu timing. I didn't mind as this was on pump gas, we then were able to get 411hp to the wheels on 100 octane.

 

Another place to check is the cam angle sensor.. I wonder if its malfunctioning or misreading.. You can disconnect the harness, make sure its clean, and plug it back in.. that "could" help things a little..

 

That's encouraging. At least it means that the car can be made to make more power. By the way, did you end up with extremely rich A/Fs? My car is running extremely rich. In all fairness, George did say that he had not tuned it finely since he was waiting for the cams to be installed before final tuning... Still, I hate to drive with a car that belches clouds of black smoke whenever I push the accelerator. That plus the 20% loss of fuel economy and the strong gas smell in the oil have me very worried...

Thanks man, at least you are coming up with some suggestions. I cannot help but to think that there must be a correctable condition for this problem.... I spoke with another highly respected tuner, and he said that 19 psi max and 18 psi sustained should be the max with 93 octane gasoline to prevent detonation.....

 

Has the valve cover ever been taken off?

If cams are improperly installed, you may have a damaged lifter which creates excessive valvetrain noise that will set off the knock sensor and pull timing or just not open and close the valve properly.

 

I see about 11.8:1 to 12.1:1 on pump gas. When I first installed the EMS w/o having it tuned it was really rich and left a black carbon deposit where the exhaust tip is in the garage. When George fine tune's it with the cams he will set up the EMS to what you want. When I drove from Kansas City to Chicago to get the car tuned we got like 180 miles to a tank of gas, that's like 15mpg or something. When I drove back from Chicago, after it was tuned I got like 20+ mpg, and I didn't keep my foot out of it all of the time because it was just tuned. The gas in the oil is normal if you are running really rich, Martin at AMS asked me about this, but he understood when I told him I was running the stock EMS calibration from when I installed it.


I am thinking that it really has to do with the big16g on pump gas. I think I was in the 20 to 22 psi range on the pump gas tune when we saw the knock issues. That turbo is just so maxed out at the 22psi range and above. I have multiple logs from the time I tuned my car to prove this. On our final pull on race gas we maxed boost out at 26 to 27 psi at 4500 rpms but after that the turbo just fell on its face to around 22-23psi at redline.

 

No, the valve cover has not been taken off to my knowledge. I've got the HKS 264 cams but they are still in the box. Perhaps there is some sort of problem such as caused by this?....

 

I don't suppose your running aftermarket pulleys?

 

Your A/Fs sound very nice and not too rich. I wonder if I could ever get the car to run safely with a/f's like that... Your experience is very similar to mine as far as the gas smell in the oil, the soot and lousy gas mileage. I was under the impression that George had indeed tuned the car already, but what you describe is some sort of rough, super rich (safe ) base map.


I'm still with the stock turbo. Based on my experience so far, I would not want any more manifold pressure that I've got already. I can only surmise that higher boost levels would only result in much worse knocking. I think that Al first noticed the knock issue and the timing pull when he did his first 3rd gear runs with the wide band O2 sensor, the Knock Link and the datalogger. Seems that you did not experience this problem until after you did all your mods.. Would this be a correct assessment?

 

No, not those either.... I wonder what this is all about..... I've heard that other EVOs have the same issues. I'm trying to bring this to light and hopefully find answers and corrective solutions...