99 V8 rough idle hot

[terrascapeinc]

Hey guys, my name is Josh, New member, but been using this forum as a reference for months. THANK YOU by the way, tons of excellent info on here! Anyways, I recently acquired a really nice black 99 SHO for really cheap, and here's what's going on... I got it from a guy who attempted to replace the transmission himself, and failed. So I got it with a brand new trans that just needed the installation finished. Done. Starts, runs, shifts, drives good, until a few weeks later. I started getting a miss when cold, pulled a number 8 misfire code, lean codes, rich codes, bought a used MC coil pack off ebay, stuck it in, the miss went away for a few weeks then came back. It gave me a number 4 code this time, so I bit the bullet and bought a set of MSD blaster coil packs (did tons of research and found out that the ford 4.6 DOHC in the SVT mustangs and some lincolns use the same packs minus the boltdown tabs, easily fixed with home made hold downs), also installed (and properly gapped) new motorcraft plat plugs all around. While I had intake apart, I cleaned everything, checked for vacuum leaks, resealed everything, changed the oil, fuel filter, replaced some iffy PCV hoses and fittings, and fired it up. Ran like a top. Until it gets warm. I now am getting a misfire on number 4 (At least I think its number 4, only occasionally sets off a code), also getting a rich system code on bank 1 after driving it for a while. And when its warm, it misses at idle about 50% of the time, even if you get on the throttle it will miss until it hits exactly 2000 rpm on the tach, then the cylinder picks up fire and the thing runs like a scalded cat. One thing I never thought to check was the compression when I was doing the plugs, but that may be forthcoming soon. So what do you think? Burnt valve on #4? or possibly a bad fuel injector or pressure regulator? I've also heard that chrome peeling off and plugging up the fuel rail is an issue sometimes(which would also make sense because if I remember right, number 4's injector is the last one on the rail). This car came from the Seattle area and had reasonably low miles so i suppose fuel system rust shouldn't be ruled out. Maybe the dreaded smashed engine harness? Any help would be greatly appreciated. I worked in a podunk town ford service department in the early 2000's but rarely saw any V8 sho's. There was only one that I knew of in town, and I never worked on it besides changing the oil once. Any info/experience you can share is appreciated. Thank you all!

 

[sperold]

Job 1 is making sure the cams have been welded.
Check for codes (current and stored) and list them here.
If it runs well above 2000 rpm, it probably has good compression.
It is not a burnt valve, the codes will tell the story.

 

[terrascapeinc]

Job 1 is making sure the cams have been welded.
Check for codes (current and stored) and list them here.
If it runs well above 2000 rpm, it probably has good compression.
It is not a burnt valve, the codes will tell the story.

The prior owner told me that the cams were welded, but I have yet to see for myself. I will be pulling the front valve cover off next weekend most likely. It has a slight oil leak that is dripping onto the front exhaust manifold and driving me nuts lol. As for codes, I have only gotten a #4 misfire code and a "fuel system too rich bank 1" code. The rich condition code has come up as a pending code several times and has come up as an active code probably three times in the past 500 miles. I drove it about 75 miles today and got no codes, pending or otherwise the whole trip. And the miss came and went probably three times as I was driving. But when I got home, it was idling smooth and perfect. It's confusing the **** out of me lol. The inconsistencies tell me its an electrical connection but I just cant track it down. I'm half tempted to make jump wires from the ecm connector at the firewall directly to the #4 injector and coil and see what happens lol.

 

[terrascapeinc]

Also just read about people having issues with the IAC valve. It does occasionally have issues wanting to stay running upon a hot restart. Maybe something to try replacing?

 

[sperold]

It is better to give us the code numbers that you are reading.

The people on this forum have experience in interpreting the code numbers that go beyond the standard description in the code book. For example, one code has a fuel system definition, but will occur anytime the engine stalls, for whatever reason.

The O2 sensors often play a role in rich and lean codes. The sensor itself could be defective and the wiring can be an issue as well, and when the Y-Pipe is removed, sometimes the sensor is mistreated.

Have a look at #4 plug to see if it is broken or fouling. Plugs are sometimes damaged during the install.

 

[terrascapeinc]

I will get the code number next time it shows up. I know that the wiring for that rear collector O2 sensor was routed weird and stretched when I got the car. I will check it out, but will a bad O2 sensor cause it to miss like that? As for plugs, they are new. I replaced them when I got the car. Then I pulled them all again when I did the coils and re-checked the gap and checked for broken ceramics or any shorting or carbon tracking. They looked good. But they didn't really have many miles on them at that point.

 

[sperold]

The miss is not connected to the O2 sensors.

I would swap the plug into another cylinder and see if the miss follows the swap, it is a long shot but it doesn't cost anything. See if you can do the same for the coil as they can be a problem as well.

Do a test with a propane cylinder to see if you have a vacuum leak, as that could explain your lean condition.

 

[terrascapeinc]

Just tore into the engine today finally.... Ran a compression test, then had a slight panic attack before I realized the check valve on my compression gauge was stuck open lol. I took care of that. But by the time I did, the engine was pretty much cold. So I pulled a pretty consistant 115-125 across the board... I figured that wasn't terrible for a cold engine. So, I went on to pulling the valve covers to check if the cams are welded. They are not. But they did have evidence of the fancy Ford loctite fix. So, I will have to bust out the welder and take care of that. But, on that note, it appears also that (at least) the front intake cam gear has slipped several degrees, and possibly also the rear exhaust cam. But shouldn't I be pulling a cam position code? I have yet to line up TDC and verify, but it seems odd. And also, I believe I have narrowed my problem down to being the wiring to #4 coil pack. No signs of arcing on the plug, coil, or boot, on any cylinder... which would also explain what I said earlier, which was that the unburned gas on 4 is just getting blown into the exhaust and causing the rich mix code.

 

[sperold]

I don't know if there is a cam position code on these engines (that keeps track of where the cam is compared to the crank position). I know our Suzuki has it and you can get an indication that the timing chain has streached and the cams are out of sequence with the crank angle, but I never heard of it on the SHO.
I would weld the cams, but I would also look for exhaust cams that have not moved and install them when convenient. You have an interesting science project there and perhaps someone will know what affect this valve overlap change has on your engine. It is bound to have an effect on performance.
Practically everyone who does a compression test on the same engine gets a different number, so with that in mind, your even numbers suggests everything is ok compression-wise.

 

[terrascapeinc]

Okay, finally got to the task of getting my marks all lined up, and I must be the luckiest V8 SHO owner ever, because, there is NO misalignment of any kind. The marks couldn't be any straighter. Gonna clean it up a bit, weld it up, and throw it back together. I am pretty excited right now. Now I won't feel like I have to baby it anymore lol. New trans, bulletproofed motor, new COP's, and my wiring fix, throwing in a new IAC valve just because, and I will have a sweet, solid SHO. And I have less than $1000 invested in this thing. Thanks for your help.

 

[leolove]

Okay, finally got to the task of getting my marks all lined up, and I must be the luckiest V8 SHO owner ever, because, there is NO misalignment of any kind. The marks couldn't be any straighter. Gonna clean it up a bit, weld it up, and throw it back together. I am pretty excited right now. Now I won't feel like I have to baby it anymore lol. New trans, bulletproofed motor, new COP's, and my wiring fix, throwing in a new IAC valve just because, and I will have a sweet, solid SHO. And I have less than $1000 invested in this thing. Thanks for your help.

What was the mileage before the welding was done