View Full Version : What am I missing here? Tech issue

07-16-2008, 07:53 PM
Starts O.K. and then as you accelerate, it goes very lean. The valves ping like a champ.

2. As you continue to accelerate, the pinging goes away around 2500 rpm. It bucks like the proverbial bucking bronc when it is in the lean condition.

I have replaced the following;
new factory plugs,
new hot coil
new camshaft sensor
new crankshaft sensor
new IAC
new Motorcraft battery
cleaned the cold air cleaner filter
brand new gas
new coil pack
new fuel filter

Additionally, I had the gas tank dropped and checked the gas line and it is where a good pick-up should be.

The problem started after I had driven about 2k miles after I did some refreshing of the engine systems.I did remove the blower to get to the valve covers to replace the valve cover gaskets. I spent a significant amount of time checking to avoid vac. leaks.

Am I on the right track by checking the fuel pressure "under load" ? Also, to re-check the I/C sealing areas and the blower sealing areas ?

Your assistance and comments are appreciated.

08-06-2008, 10:59 PM
This is Lee, now in SD.

Do you have an oscillating idle?

Is there hesitation when you first start off normally?

Does it happen with medium ( no boost )?

The answers may help to isolate a leak before/after the SC.


08-06-2008, 11:07 PM
disconnect the maf and reset the comp.. see if it makes any diff

08-07-2008, 10:38 AM
run codes ill bet its coming up lean condition left right bank on my old sc it was caused by oxy sensors / bap sensor that thingy up on cowl pass side its the same unit used on n/a birds only we have a spongy filter on ours bap map same part one has a sticker over the part number

just my o2 as ive had this happen dont know if it was the oxy sensors or the map/bap i replaced them at same time .

08-07-2008, 11:15 AM
I have a fuel pressure gage that fits on the stock fuel rails. You want to use it? o2 sensors would be my guess.

Coast to Coast SC
08-09-2008, 12:30 PM
Why do you think it is lean? If everything else is as it should be there are three things I can think of.

First would be old and tired (or abused) O2's. If this motor ever blew HGs and dumped coolant on them, they tend to get grumpy shortly thereafter.

Second would be a dirty MAF. You run a cold air set-up right? Do you have to oil the filter element? Everyone (myself included) over oils them and the oil mist that they produce then coats the filaments inside the maf leading to lower than expected air flow readings and, you guessed it, lean mixtures.

My third guess is a failing cat. However I would doubt this one if the condition is indeed going away at 2500rpm+. On the old streak, near the end of our partnership, it would rattle like a spray can when cold. When the engine temp came up and the computer started looking at all the sensors, it could compensate for the skyrocketing combustion temps but that death rattle cost me a few sets of HG's. New cats made the problem disappear.

Good karma is the solution. Imagine the good karma you would be generating by setting Al up with that daughter of yours! Before that though I think I would dump the O2s if they have over 30,000 miles on them or have gotten a coolant bath ever and clean the maf with some electronic contact cleaner (Radioshack 64-4315). Checking fuel pressure is a good idea although if the ping is going away at higher RPMs, I doubt it is a fuel pressure issue. Good luck Ron. Keep us posted!