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I am having a very small detonation problem (if you call ANY detonatation "small") and could use some guidance. Here is the story.
1988 TC 5 speed with 62K miles...original owner. Motor is stock except for a K&N cone filter and a 180* thermostat. Car has never given a hint of any problems, detonation, etc. A recent tuneup of Motorcraft parts (e.g., plugs [gapped], cap, rotor, wires, timing belt, timing belt tensioner, fuel filter)was completed. Compression test shows all cylinders between 142 and 160 psi on a cold motor (no. 4 was the lowest, no 1. was the highest). Vacuum at idle is a steady 19.5 inches Hg and vacuum spikes to 22-23 inches when the throttle is snapped closed from 2,000 + rpms. No codes whatsoever....11 all the way around. Timing set at 10* BTDC with spout out and car runs fine just like it always had. Car always showed 15 psi boost on the stock guage. No detonation whatsoever.
I ran the car for about one week after the tuneup with no detonation and then installed a Gillis Valve. Boost was set to 15 psi with an accurate aftermarket guage (which just happened to agree with the stock boost guage...so overall boost level didnt change much if any). Now I am getting a very minor amount of detonation only at WOT at rpms between 3,000 to 4,000. I don't here it above 4,000 rpm if its present. The detonation is so slight and is NOT always audible.
Thinking it was the fuel, I tried dry gas, changed fuels, fuel system cleaner, etc., but the detonation is still present.
Ran the fuel system test after Pete so kindly emailed me the procedure (thanks again Pete). Fuel system test results were as follows:
a. KOEO FPR vacuum line connected showed 40 psi with pump running. As soon as the pump is turned off, the guage drops to 38 psi and then will hold 38 psi for an excess of 5 minutes.
b. KOER FPR vacuum line connected 30 psi.
c. KOER FPR vacuum line NOT connected 40 psi.
e. Driving conditions under full boost shows 55-56 psi.
d. Fuel pump pressure immediately after fuel filter 98 psi.
e. Fuel pump delivery rate immediately after fuel filter between 85-90 ounces of fuel per minute (no restriction so pressure is minimal).
Based on the above, everything appears to be in order, but I would like to increase boost to 16 -16.5 psi with a bit more timing, say 12* BTDC, without detonation.
Now my questions.....
1. While the detonation could be a result of almost anything, I really don't feel like chasing down the smallest of possible gremlins if installing a Kirban adjustable FPR would likely solve my detontation problems. What do you think? Would installing an adjustable FPR give me the fuel to cure the detonation with the increased boost and timing?
2. Would the Kirban model no. KIR5005 (fits '86 to '93 Mustangs) be a direct replacement for the stock FPR without modification? Here is the link to the part......
[link]http://www.jdsperformance.com/index.asp?initemuid=147&fcmd=item&inmake=all [/link] (crap, sorry, dont know how to post a link)
3. If the Kirban it is not a direct replacement for the stock unit, where/how do you mount the Kirban FPR?
Thanks for reading the post and thanks in advance for any assitance/recommendations.
[This message has been edited by Rockhead (edited 08-31-2003).]
[This message has been edited by Rockhead (edited 08-31-2003).]
[This message has been edited by Rockhead (edited 08-31-2003).]
1988 TC 5 speed with 62K miles...original owner. Motor is stock except for a K&N cone filter and a 180* thermostat. Car has never given a hint of any problems, detonation, etc. A recent tuneup of Motorcraft parts (e.g., plugs [gapped], cap, rotor, wires, timing belt, timing belt tensioner, fuel filter)was completed. Compression test shows all cylinders between 142 and 160 psi on a cold motor (no. 4 was the lowest, no 1. was the highest). Vacuum at idle is a steady 19.5 inches Hg and vacuum spikes to 22-23 inches when the throttle is snapped closed from 2,000 + rpms. No codes whatsoever....11 all the way around. Timing set at 10* BTDC with spout out and car runs fine just like it always had. Car always showed 15 psi boost on the stock guage. No detonation whatsoever.
I ran the car for about one week after the tuneup with no detonation and then installed a Gillis Valve. Boost was set to 15 psi with an accurate aftermarket guage (which just happened to agree with the stock boost guage...so overall boost level didnt change much if any). Now I am getting a very minor amount of detonation only at WOT at rpms between 3,000 to 4,000. I don't here it above 4,000 rpm if its present. The detonation is so slight and is NOT always audible.
Thinking it was the fuel, I tried dry gas, changed fuels, fuel system cleaner, etc., but the detonation is still present.
Ran the fuel system test after Pete so kindly emailed me the procedure (thanks again Pete). Fuel system test results were as follows:
a. KOEO FPR vacuum line connected showed 40 psi with pump running. As soon as the pump is turned off, the guage drops to 38 psi and then will hold 38 psi for an excess of 5 minutes.
b. KOER FPR vacuum line connected 30 psi.
c. KOER FPR vacuum line NOT connected 40 psi.
e. Driving conditions under full boost shows 55-56 psi.
d. Fuel pump pressure immediately after fuel filter 98 psi.
e. Fuel pump delivery rate immediately after fuel filter between 85-90 ounces of fuel per minute (no restriction so pressure is minimal).
Based on the above, everything appears to be in order, but I would like to increase boost to 16 -16.5 psi with a bit more timing, say 12* BTDC, without detonation.
Now my questions.....
1. While the detonation could be a result of almost anything, I really don't feel like chasing down the smallest of possible gremlins if installing a Kirban adjustable FPR would likely solve my detontation problems. What do you think? Would installing an adjustable FPR give me the fuel to cure the detonation with the increased boost and timing?
2. Would the Kirban model no. KIR5005 (fits '86 to '93 Mustangs) be a direct replacement for the stock FPR without modification? Here is the link to the part......
[link]http://www.jdsperformance.com/index.asp?initemuid=147&fcmd=item&inmake=all [/link] (crap, sorry, dont know how to post a link)
3. If the Kirban it is not a direct replacement for the stock unit, where/how do you mount the Kirban FPR?
Thanks for reading the post and thanks in advance for any assitance/recommendations.
[This message has been edited by Rockhead (edited 08-31-2003).]
[This message has been edited by Rockhead (edited 08-31-2003).]
[This message has been edited by Rockhead (edited 08-31-2003).]