MrNuke

Hi all, back from not posting in a while. My question is this :
I have replaced my Knock sensor in my '85 vette a few months back, and I could swear my performance has been dropping. the car feels fine when I punch it at low rpm's, but once I hit around 3500+ rpms, she sounds liek the timeing gets way retarted. Deep and louder exhaust tone too. The initial timeing of 6Degrees advanced has not changed since I got the custom chip in the car years ago, so thats the same. My Fuel pressure lives at 43psi, and bumps to 54 when I go WOT, so that checks out. I have a brand new High-Flow CAT installed 4 months ago, so thats not clogged. Before the knock sensor was replaced she pulled VERY strong till about 4800rpms. My valves do make some clicking noises I have noticed.

Thanks for any info guys (and gals).

MrNuke :crazy:

GlockLT4

Hook up a computer to your ECM and you should be able to get the proper readings.

Rick86

Just because you don't hear the knock does not mean it is a false knock.

Vic'89

You need a scanner hooked up to see if you are getting timing retard.

If the computer is pulling timing, you will go slower.

Vic

MrNuke

Hmm true..

So other than spending hundreds or thousands of dollars on a diagnostics computer how can I check that out?

:crazy:

65Z01

Check out the ECS upgrade on my site. It eliminated my knock problem and it still detects true knocks (I advanced base timing to beyond +12 deg just to test it out). After this ECS upgrade, I just a HyperTech Stage II chip and with +6 deg base timing I get one knock count at 5,400rpm on a WOT run. So I think she is just about right.

BTW, you can get free scanner software or buy an AutoXray for about $200 or so to scan your ECM via the OBD-I connection. When you compare shop flat rates for diagnostics vs cost of a scan tool and several good books, you find that the tool quickly pays off.

MrNuke

Thanks for all the help guys.
One part than I am NOT at all familiar with is my car's computer /ECS (although thats funny as Im a computer system engineer).
Anyways, Ill probably get an AutoXray soon to check it all out.
:seeya

JAKE

That's good info on the ECS upgrade, I'm going to give it a try.

How much was it?

Jake

Aaron's 87

Your 'custom' chip probably has too much timing - a common problem for 'custom' chips. Make a real chip.

Check your plugs for signs of detonation.

65Z01

Jake, I think it was about $70-$80 retail but my GM parts guy gave it to me a jobber's rates or ~$52.

JAKE

Right. I went to Chevy yesterday and they wanted $84.00 plus tax. I found out it's for 85/86 "B" and "G" body GM cars.

I then went to O'Reilly's Auto Parts and they checked and have a Borg/Warner - # ESC109 - for $55.60, but it's not available nation-wide and is factory back order.

Bad news both ways.

Jake


[Modified by JAKE, 4:34 PM 9/11/2001]