need a guru's help with detonation PLEASE!!

R

rich9521

New Member

Feb 24, 2002

12

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0

Apr 19, 2004

#1

• Apr 19, 2004

• #1

All was fine till I changed the heater core. Now at 3500-4000 wot it detonates. Runs rich all the time but detonates only at wot. I replaced map sensor and ect with no luck. It is a 88 gt tfs intake edelbrock heads msd ignition and a paxton sn-92. Yes I checked for vacume leaks holds 17 pds at idle. Can't find a leak anywhere and I checked all the maf conversion wiring and still nothing. pulls no codes except for typical egr stuff. Please help!!!

 

M

MustangvertGT

Founding Member

Jul 17, 2002

122

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0

Montebello, Cali

Apr 19, 2004

#2

• Apr 19, 2004

• #2

When i first got my car, its timing was way off and it would detonate as well, even with 91 octane. I just set it back a few degrees and it fixed the problem. Could be as simnple as that. But I dont see how a heater core could mess with your timing. Just throwing that out incase you havnt checked

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

33

129

Apr 19, 2004

#3

• Apr 19, 2004

• #3

since the core is in the region of the puter and harnesses for the puter, any chance wiring was messed with?
otherwise, back off timing and see what happens. might want to put a fuel pressure gauge in to see if you are losing pressure at WOT and running lean...
good luck.

 

R

rich9521

New Member

Feb 24, 2002

12

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0

Apr 21, 2004

#4

• Apr 21, 2004

• #4

double checked all wiring and fuel pressure is around 44 pounds ...same as when I dynoed it.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

33

129

Apr 21, 2004

#5

• Apr 21, 2004

• #5

what is the pressure when you are seeing detonation? you could be leaning out higher up in the RPM band, and seeing detonation...just an idea.


good luck.

 

R

rich9521

New Member

Feb 24, 2002

12

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0

Apr 22, 2004

#6

• Apr 22, 2004

• #6

about 44 psi...got a sugestion on heat range...

 

dastang2

Active Member

Dec 11, 2003

2,020

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46

tx

Apr 22, 2004

#7

• Apr 22, 2004

• #7

how about a bad msd box, it happens frequently.

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

79

Charlotte, NC

Apr 22, 2004

#8

• Apr 22, 2004

• #8

"Typical egr stuff" -- very common side effect of malfunctioning egr is detonation. The engine runs hotter in the chamber than the computer designers expected (egr cools the chamber during combustion), often with too much timing added by the computer when the exhaust it expects to be present in the intake mixture isn't present because the egr's not working. The result is often detonation.