1994 5.0 High Output problems

[Realest5.0]

My 94 GT 5-spd. detonates at around 3500+ RPM when I get on it any harder than just cruising speed. In the meantime, a dirty grayish cloud of smoke appears behind me. I'm assuming it's coming out of my exhaust. It does not do this as much within the first 5 minutes after startup. Besides checking my timing, what else may be wrong? Thanks guys.

[mustang-madness]

sounds to me like lack of fuel. not sure why, but its a road to follow. check fuel pressure, injector impedance, do an injector balance test with a code scanner. check your tps sensor while you're at it. timing advance might also be locked out. bad ignition module can do that. see if the spout connector is plugged in. that's about all i got. good luck.

[Realest5.0]

I'll check all of that at work. The motor has nearly 200,000 miles on it to. That isn't helping at all. Anything alse that anyone wants to add?

[1nice70]

Chek for cross fire from the plug wires.I had this same problem with my truck and I thought the guys were on crack when they told me, but it worked. I have sence found it was a TSB from ford also.

[Realest5.0]

It has brand new Ford Racing wires on it. Do you still think that they would crossfire?

[1nice70]

I had it happan. Just make sure that cyl's that fire next to each other are away from each other.

Sorry I looked for the TSB, but could not find it.

[1nice70]

OK, I found this... I know it's for trucks, but same engine. Sorry No pic's.

LIGHT TRUCK: 1987-1994 BRONCO, E-150, E-250, F-150, F-250


ISSUE:
Engine miss, spark knock, buck/jerk, surge and other driveability concerns may be caused by induction crossfire. This occurs because of improperly routed spark plug wires.

ACTION:
If spark plug replacement is performed, the correct firing order and spark plug wire routing is essential to prevent the possibility of induction crossfire between cylinders. Refer to the following procedures for inspection of the spark plug wire routing and firing order. Properly reroute the spark plug wires if required.

FIRING ORDER

The firing order for 1987-1993 vehicles is 1-5-4-2-6-3-7-8. If #7 and #8, or #2 and #4 spark plug wires are routed next to each other at the separation bracket, an induction crossfire condition can occur.
The firing order for 1994 vehicles is 1-3-7-2-6-5-4-8. On these vehicles the #1 and #3, or #5 and #6 spark plug wires must be separated to eliminate the possibility of an induction crossfire.
To eliminate the possibility of the coil wire becoming disconnected, route the coil wire under the spark plug wires at the distributor cap.
1987-1993 VEHICLES

Inspect the routing of the spark plug wires. Refer to Figures 1 and 2.


Figure 1 - Article 94-4-10




Figure 2 - Article 94-4-10


Make any spark plug wiring corrections as required.
1994 VEHICLES

BRONCO OR F-SERIES

Inspect the routing of the spark plug wires. Refer to Figures 3 and 4.


Figure 3 - Article 94-4-10




Figure 4 - Article 94-4-10


Make any spark plug wiring corrections as required.
E-SERIES

Inspect the routing of the spark plug wires. Refer to Figures 5 and 6.


Figure 5 - Article 94-4-10




Figure 6 - Article 94-4-10


Make any spark plug wiring corrections as required.

[Realest5.0]

That all seems helpful. I'll try to check all of this asap. I wish someone had the Mustang bulletin w/ pictures.

[ninety15.0]

Also try cleaning your MAF element. These wires get gummed up with air filter oil, dirt, etc...the SN MAF's are notoriously bad for causing detonation due to dirty elements. Take a Q-tip and some electrical contact cleaner...and clean the wire elements. Should do the trick. good luck

[ajh]

With 200K on the engine you might want to check the harmonic balancer to make sure it has not slipped (rubber coming our of back) and that timing is where you think it is.

[Realest5.0]

I have done some thinking. My problem could be stemming from multiple things:

1. Fuel pressure issue (FPR or fuel pump)
2. Injector imbalance (clogged or worn out injectors)
3. TPS sensor issues
4. Ignition module issues
5. MAF contamination
6. Crossfiring
7. Cooling issue (thermostat or water pump) Although, my temp stays on the low side of normal.
8. Vacuum leak causing EGR to not function properly. (This one makes the most sense. I do have a pretty good sized vac leak right now.)
9. Timing issue (My current balancer has only been on for less than 10k miles, so I don't think that would be an issue. Although, my timing may be advanced for some other reason. What is the factory timing setting?)

Thanks for the help. What do you think about my list of crap to check? I just need to find time to look at my car now. Sometimes it sucks being a full time student and working until 7 every night.

[gadget73]

I'd fix the vacuum leak first. Not only will it possibly cause EGR issues, it will cause a lean condition by sucking un-metered air that the ECM doesn't know about. The fuel won't be richened up to account for this additional air and that lean mix could cause detonation as well.

10 BTDC with SPOUT unplugged should be stock timing. I believe its on the sticker on the fan shroud though.

[Realest5.0]

Good deal. Thanks for the help. That's what I'll attack first.

[Michael Yount]

The very first thing you should do is to quit guessing and pull the codes....the computer has significant diagnostic capabilities built in and they're there to help you diagnose problems so you won't have to guess. Part throttle detonation if often egr-failure related. Although, at 200k, there could be any number of issues -- not the least of which is combustion chambers/piston tops that are pretty dirty. The carbon deposits can create hot spots that contribute to detonation.

Pull the codes....