at WOT its detinating very bad. with base timeing set at 6 advanced. so i set back. all the way back to 0 just to stop it. this seem to me to be set back more than i should have too.

mods are
350 .030 over
crane cam 2030
3 angle valve
1.6 roler tip rockers
new valve springs
10:1 competion
ported plenum
K&N
new injectors (stock)
stock heads
stock chip
stock headers

i also thought that my 1/4 times were slow also 14.4 @ 95 60'@2.134 RT .612

is it just me or what

 

your knock sensor probably took a dump on you, either that, or your ESC might have also. I just got do fighting this, battle, but before you replace anything check your wire connect, it might be loose or something simple like that.

 

Well you're running the stock chip and stock injectors right off the bat which might or might not cause these problems but then again it can't help with a motor with a lot of mods. Does your car use a speed-density system ('90-'92) or an earlier MAF system. You're motor is moving a lot more air than in "stock" form and your fuel isn't keeping up which is causing a lean conditoin=detonation. How hot was the motor when you ran it?

Also, you're running 10:1 compression with iron heads......

 

the car is a 89 with MAF. i have a AFPR set at 48 psi. i have tried higher and lower. 48 seemed to be the best at the track. I have no codes saying if i am rich or lean. i only run 94 octane gas. i am running 160 stat.and fan switch. the car temp is cool all the time.never over 100c. every one i talked to seem to think that 10:1 compression with iron heads would have been ok...but maybe it is to high.

 

Sounds similar to my problem. ZZ4TPI. Getting knock counts and timing retard on anything over 20% throttle under load. Good fuel pump and deliver as far as I can tell. (new pump and fuel gage shows no loss under load.)
I'm looking in the helms at the knock sensor test procedures and give that a try.

 

I have noticed a disturbing trend with crane compu cams and detonation. I've spoken with quite a few people who have a 2030 and they knock. Including my old 305, it knocked after the cam no matter how much fuel you added or took out. I too ended up running 0° base timing to duct tape cure the issue. Untill one day the engine beat itself to death.

 

The computer will advance timing about 5 additional degrees during WOT operation. Have you considered any PROM burning equipment?

Are you still running EGR? The computer will also advance the timing when it 'thinks' the EGR valve is opening. If you're not getting the cooling effect of the EGR, it will be too far advanced.

 

tpi_roc
So what your saying is that you think its the cam and there nothing that i can do?

AlexJH
I still have the EGR i just did my etest and passed by a mile. the EGR is working fine. At 6 base I dont even need to be at WOT to detonate.
i just got my parts in today to build a cable for my laptop. i have spare chips on order i hope by the weekend to be scanning the computer

 

nonono

Dont get me wrong there at all....


The cam added to an otherwise semi-stock engine has seemed to cause this alot, but I pretty much fixed it running 0° base.

With prom burning the whole problem is fixed.

You need to burn your own proms anyways, that would be like a carbuerated engine owner not having a screw driver.

 

Good luck with the scan tool, there's so much stuff going on, you'll be amazed.

I found out about the EGR the hard way, the previous owner had disconnected it (but it still passed AirCare).

 

I have the same problem with detonation. Mine only occurs when the temp. guage reads hotter than 200*. The problem started after it had been sitting for about 5 months. It started before I removed the EGR and AIR, and that didn't seem to make it worse or better. I also have the compucam with base timing set at 6*. I thought that my valve springs were just crapping out(I think the origionals were reused when I had the heads done). The ses light comes on and sets codes 42 and 43. trigger GTA, I would definately like to know if you figure out a soulution to this problem.

 

I strongly recommend trying out 0° base timing.

If nothing else it will help you locate the problem, if your detonation doesn't go away or start at a later rpm, then you know its not timing related.

 

tpi_roc
i see what you are saying the more i set my timeing back the higher the RPM before it starts to detinate. but i still think that with my mod i should have had faster 1/4 times and speeds. could this be an indecation of some other problems?

 

No

Detonation is physically fighting against you

As your piston comes up your timing is firing off before your piston reaches top dead center, basically at a higher rpm this is good because this takes up for lag time in your ignition and in the flame travel of your combustion, however as soon as you break through the "TO MUCH" barrier your now completely exploding your Air/Fuel intake before your piston has come up over TDC and its pushing back down and against your other cylinders...

Obviously this breaks things, and naturally hurts power, tweaking your timing keeping it just on the "Safe" side of detonation is how you perfect your spark curve.

I say deffinatly start on fixing that, then from there you can move forward, But i'll bet you become happier with your engines performance.

 

I also just noticed two things I skimmed over previously without paying any attention too.....

1.) 10:1 compression
2.) stock heads.

10:1 Is a pretty tall order for pump gas these days, ESPECIALLY on cast iron (stock) heads. Cast iron will retain heat in the combustion chamber (which is good) far better than aluminum will, however that heat brings "hot spots" and "hot spots" bring detonation. I personally wouldn't run 10:1 on a daily driven street car, 9.5-9.75 would however be fine. I CERTAINLY wouldn't DREAM of running it without a scanner, and prom burning equipment IN HAND. LB9's seem to detonate stock.. but to take an L98 and up the static, AND dynamic compression with a stock timing curve just screams to be detonated. If you dont cure it you'll break something, and the whole time it detonates you're robbing yourself of potential power.

Another note on all this stuff is knock can also be inaudiable, you can be combusting before TDC, but still not ENOUGH of the combustion happens before TDC to make it *knock* so that a human can hear it, however this still can/will rob power and over a long period of time also cause undue wear.

This is what knock sensors and scan tools are for, to retard your timing previous to any detectable knock.

Good luck

 

I thought i'd add this as well. Your exhaust side is still basically stock eventhough on the intake you've done a substantial amount of work with a new cam and so fourth and the engine is moving significantly more air, as stated before. But here's the problem, those crappy stock manifolds and everything behind them isn't going with the "flow" (pun intended), creating a ton of back pressure as your motor is trying to move more air. That means there's a lot of heat and pressure that isn't getting out of the combstion chamber, which is causing a ton of knock. 10:1 compression with iron heads is pushing it but it is "do-able" if you set it up right. I'd highly recommend getting a good set of headers and replacing the rest of that restrictive exhaust system.

 

ok i just got a code, 32 or EGR. so i will look into this first. i laso got another code 42 but it may have been when i set the timing and forgot to clear the computer

 

BTW the SES is not on all the time and seems to be intermittent.
the idle seems to come down about 150RPM as wll when the SES is on.

 

i think this post has helped me in my search to cure my problem with detonation too. i have an '87 LB9 and im running an INSANE 18 degrees advanced. maybe ill try 14-16, didnt seem to have the problem with the stock 12. but i also wanna up my performance from stock, so the upped timing helps. hell, even with detonation i STILL outrun new Pusstang GT's!

 

sigh...

 

We all know detonation is perfectlly acceptable in the name of beating one mustang

 

by the way.....









YOU'RE FIRED!!!!

 

well it still has not helped. i still have the same problem. and the egr thing was not the cause of it