Pinging Blues

[Dante30]

I have a 94 Gt that has approx 140k miles, the pinging started little by little around 110k miles. Over time it has worsened. I live in San Diego, on a 70 degree spring day w/ 91 octane, it will ping at wot. I have changed the act sensor, the coolant sensor, plugs, wires, fuel pressure regulator, fuel filter, maf (and cleaned it), tried Sea Foam, all of this to no avail. The car has always passed smog, and generally runs fine, for normal driving. I just can't get rid of this stupid detonation!! Any Help would be appreciated!!! I love my stang, however, I'm loosin' faith!

Help!!!!

 

[HISSIN50]

Are you able to monitor fuel pressure at WOT (during greatest fuel system demand)? I ask because I didnt see an actual fuel pump listed in your parts-replaced synopsis.

Also, have you tried backing the timing down a hair?

Good luck.

 

[Dante30]

Re: Pinging

Are you able to monitor fuel pressure at WOT (during greatest fuel system demand)? I ask because I didnt see an actual fuel pump listed in your parts-replaced synopsis.

Also, have you tried backing the timing down a hair?

Good luck.

I have not replaced the Fuel pump, I do have a gauge on the fuel rail, about what do you think the pressure should be at wot? Also, the timing is exactly where it should be for stock timing on a 94 gt. It pings so bad some times, I thing backing timing down a hair wouldn't be enough. On cool mornings, the car seems to run w/o pinging, but as it nears normal op temp, then it will ping. If I put regular unleaded in it, it will ping at 1/2 throttle!!!! I'm mystified!!!

 

[HISSIN50]

I have not replaced the Fuel pump, I do have a gauge on the fuel rail, about what do you think the pressure should be at wot? Also, the timing is exactly where it should be for stock timing on a 94 gt. It pings so bad some times, I thing backing timing down a hair wouldn't be enough. On cool mornings, the car seems to run w/o pinging, but as it nears normal op temp, then it will ping. If I put regular unleaded in it, it will ping at 1/2 throttle!!!! I'm mystified!!!

Pressure should be 38 PSIG at WOT (when you check fuel pressure with the vac line removed from the FPR, you're simulating a WOT condition with regard to the FPR bypassing fuel).

That part about the conditions is interesting. A couple thoughts: Have you installed a real temperature gauge to see how hot you're engine actually is? The stocker is pretty to look at, but not much else. You could be seeing an onset of a preignition-type situation due to crap in the CC's and a hot engine.

I'd note that fuel pumps tend to show their weakness when they get hot (the diaphram gets loosey-goosey) but they tend to degrade quickly - it does not sound like yours is.

You might want to search "Seafoam" and see if that's something you'd like to try. I'm leery of those products but so many folks have had success with it (and a few have claimed that issues arose after using it)...............

Because the processor on these cars is load based, that's good that you commented on the part throttle aspect (though with a more volatile fuel being used). Your timing-advance can actually be higher at part throttle than when you press deeper into the pedal. This doesn't help pinging.

If you haven't, please pull codes. Codes can be stored without illuminating the CEL. But something like a lean (O2) code could be telling.

Random thoughts.
Good luck.

 

[DoctorB712]

I totally understand your issue as the exact same thing happened to me (95 GTS with 150000km). I also changed pretty much all the sensors, fuel pump, fuel pressure regulator, and so on. After much $$$ and effort cleaning the MAF was the most helpful in my situation but the problem was still present.

From what I learned last year when I fixed the problem is that the fuel tables on the GT are a little on the thin side of things and this is an issue with GTs but not with Cobras. The reason is that the cobras have fatter fuel tables. Solution: Tweecer running cobra file fixed ALL my pinging issues.

A little note: Cobra file has 24# injectors and the spark table values are lower than the GT. However, a few clic of the mouse and the table can be optimized.

I hope this helps.

 

[95BLKGT5.0]

I have the same problem and have changed everything y'all have posted.
I don't have a tweeker so how can I fatten up the fuel tables?

 

[Dante30]

Early in morning, after I posted "pinging blues" I surfed the net looking for more info on the problem. I'm not sure if I found an absolute solution, however, Some say that a few of the 94's & 95's Gt's came out from the factory w/ V6 fuel pumps. Now I don't know how one can prove that it is true or just another urban legend! My problem w/ that theory is that this problem, at least on the internet, appears to be quite common, and I've heard that some of the 4.6's also have that problem. Another thing I have heard about, is that the EGR valve on our cars can get clogged or dirty on the inside, causing a plethora of issues. That sounds a little more tangible to me, except that I used up a full can of sea foam in the gas tank, and it's supposed to clean carbon out of your engine, some people swear by the stuff, but it didn't fix the problem for me. I kinda like the idea about using a tweecer, personally, I wonder if that would affect Smog tests, here in California?

 

[HISSIN50]

You can use a TwEECer to have whatever tune you desire (including an OEM tune), so emissions testing shouldn't be affected per se.

 

[Dante30]

Still Pinging!

Pressure should be 38 PSIG at WOT (when you check fuel pressure with the vac line removed from the FPR, you're simulating a WOT condition with regard to the FPR bypassing fuel).

That part about the conditions is interesting. A couple thoughts: Have you installed a real temperature gauge to see how hot you're engine actually is? The stocker is pretty to look at, but not much else. You could be seeing an onset of a preignition-type situation due to crap in the CC's and a hot engine.

I'd note that fuel pumps tend to show their weakness when they get hot (the diaphram gets loosey-goosey) but they tend to degrade quickly - it does not sound like yours is.

You might want to search "Seafoam" and see if that's something you'd like to try. I'm leery of those products but so many folks have had success with it (and a few have claimed that issues arose after using it)...............

Because the processor on these cars is load based, that's good that you commented on the part throttle aspect (though with a more volatile fuel being used). Your timing-advance can actually be higher at part throttle than when you press deeper into the pedal. This doesn't help pinging.

If you haven't, please pull codes. Codes can be stored without illuminating the CEL. But something like a lean (O2) code could be telling.

Random thoughts.
Good luck.

Today I checked the Fuel pressure,w/ Vac line removed from the regulator, It consistently read 38 psi, however, w/ the Vac line plugged back in, I'm getting about 30 psi at Idle and it increases as you step on the petal, up to about 38 psi at wot. I guess I should pull codes next.

 

[HISSIN50]

Today I checked the Fuel pressure,w/ Vac line removed from the regulator, It consistently read 38 psi, however, w/ the Vac line plugged back in, I'm getting about 30 psi at Idle and it increases as you step on the petal, up to about 38 psi at wot. I guess I should pull codes next.

That's normal. FP readings can be thought of as inveresely proportionate to manifold vacuum (at idle, it's 30ish. At WOT, when manifold vac is low, it jumps to near 40 PSIG). Were you able to view fuel pressure at WOT when the car was actually pinging? Testing in the garage doesnt put any load on the engine (where a failing pump shows that it cannot deliver the needed volume).

Code retrieval sounds like a great plan.

Good luck.

 

[Dante30]

That's normal. FP can be thought of as inversely proportionate to acceleration (at idle, it's 30ish. At WOT, when manifold vac is low, it jumps to near 40 PSIG). Were you able to view fuel pressure at WOT when the car was actually pinging? Testing in the garage doesnt put any load on the engine (where a failing pump shows that it cannot deliver the needed volume).

Code retrieval sounds like a great plan.

Good luck.

I was unable to observe the F.P while the car is pinging, cause my gauge is under the hood and I actually haven't been able to get it to ping while reving it in the driveway, It seems like it needs to be under load or something, I'm going to have to take it somewhere to have the codes pulled, or buy something to do that with? I have a Pro-M 75mm MAS on the way, I wonder if that will affect the pinging ,like get rid of it. I bet it will not. Fun Fun Fun!