Ecu flash and knock.

[re-rx7]

So i got my T28 installed along with a Walbro 255, Evo 560cc injectors. Got it up on the dyno to get tuned and we ended up making about 6 passes. We were at 15 psi and I could have went higher but, i was getting knock at 6k rpm. Right at 6k rpm on every pull I would get varying counts of knock from 4-14 counts. Up till that point everything is fine. We messed with timing and everything but just could not get rid of it. Right now im at 13 degress of timing max on 93 octane.

I could really use some information if any of you guys care to post.

 

[92AWDHX40]

Kinda vauge question be more specific as to you knock, how is it tuned?

 

[re-rx7]

I had Steve Kan tuning it her in the dallas area. I really didnt have a hand in it. All i know is that it was max 13 degrees and about 15 psi. It's really linear all the way to 6k rpm (curve) and then it suddenly pulls timing at 6k rpm(each run was diff but varied between 4-14 counts each time). Im gna try and get him to email me the runs. Made 220 whp and 230 tq on a mustang dyno.

 

[RayRay32]

Do you have a log?

 

[m_0ney_pit]

I didn't see a front mount or WI in your mods list, do you have either?

 

[livedsm4g63]

Full exhaust?

 

[RayRay32]

Rather than playing the guessing game, what mods do you have?

 

[re-rx7]

Full bolt ons, big hahn smic, greddy bov and piping. I found my #1 plug gap closed. Which may have been the problem. I dont knw whats causing it because there are not any marks from it being hit. Arrgghh

 

[Zack Huffman]

The plug gap closing is most likely from excessive heat and carbon buildup, which means you're probably burning a lot of oil in that cylinder. Carbon buildup can create interference with the electrode and when bad enough, it will actually increase compression ratio in that cylinder. That leads to too high cylinder temps, excessive cylinder pressure and knock.

You need to perform a leakdown test.

 

[re-rx7]

Makes sense thanks for shining some light on the subject. I put a spacer on it and it seems to be doing better but thats a bandaid. Im not saying any kind of oil residue on my plug. Would I zack? That could be the cause of the knock as well and it not being consistent. Hmmmm

 

[Zack Huffman]

You may or may not see any oil on it, but it would probably show signs of detonation, the heat coloring would be more than normal and most likely the plug would also have a lot of carbon on it if it's been used very long. Got a picture of the plug?

 

[re-rx7]

I will take one and post. I changed them not long ago for the dyno. They are a lil pale but they all are. My a/f was mid 11 flat through all the runs.

 

[re-rx7]

Update: At WOT I can only run 8 degrees of timing max anything more and I get knock from 6-12 counts which was always around the 6k rpm mark. My AFRS I adjusted from 10.5-11.1 and no difference. Car just didnt want timing. I dont understand it. I made 225 (240-250 dynojet) whp on a mustang dyno on 17 psi. If I could run more timing this would have been alot better. Plug problem was solved by going back to bpr6's no more gap closing.




My mods are:
T28
560cc injectors
wally 255
full bolt ons