Low vacuum, poor idle

[974X4BLACKSPORT]

" All that said, it behaves like it's running extremely rich rather than lean. O2's indicate a rich condition, and on a warm restart I have to go to WOT to clear out the cylinders before it will fire."

That is A problem, if not THE problem your trying to solve. Definite fuel delivery issue here, either wrong size injectors, leaking injector/s, bad spray pattern, or wrong firing sequence.

 

[fastpakr]

Why would that be the cause and not a symptom?

 

[974X4BLACKSPORT]

If you have to WOT to "clear flood" to start when warm, this means an incorrect air fuel ratio due to to much fuel for one reason or another. Check your spark plugs, I bet they are BLACK!

 

[fastpakr]

I understand that I'm getting too much fuel. What I'm not clear on is whether that's causing the other issues or caused by them. Also, surprisingly, the plugs aren't particularly black.

 

[974X4BLACKSPORT]

I can see where an ECT sensor reading in the deep "negatives" could cause the symptom of a rich restart when warm.

 

[fastpakr]

Sure, but it isn't reading incorrectly. From the OP: "IAT and ECT numbers look correct."

 

[974X4BLACKSPORT]

Are the injectors the same ones that where in it before the rebuild?

 

[fastpakr]

I understand you're trying to help, but I've answered that a couple of times already. Yes, the injectors are the originals.

 

[boominXplorer]

What does the short term fuel trims at idle read? (STFT on scanner)

 

[roscoe 0202]

I think I would get a degree wheel and check if the cam is right to the crankshaft a retarded cam would my guess
roscoe

 

[fastpakr]

What does the short term fuel trims at idle read? (STFT on scanner)

I have some screenshots on my phone from testing that about a month ago when I first started chasing this down. At the time, long term was around 15% and short around 1% (both banks were similar). If I get a chance I'll retest and update this evening.

I think I would get a degree wheel and check if the cam is right to the crankshaft a retarded cam would my guess
roscoe

Right now that's my gut instinct as well. Was just hoping to eliminate any other obvious causes before tearing things down that far. Thanks for the feedback.

 

[CDW6212R]

I think I would get a degree wheel and check if the cam is right to the crankshaft a retarded cam would my guess
roscoe

Or a spun balancer could alter the cam timing too. Take a close look at the balancer and be sure the outer ring seems perfectly attached to the inner ring. If it looks good and the mileage isn't too high, leave that til last.

 

[fastpakr]

The balancer was not replaced initially, and as far as I know has 250k miles. I'll go ahead and plan to replace it while everything is apart just to be safe.

IGNORE: Do you know what the difference is between the Powerbond 'Premium' and 'Street Performance' balancers is? Premium is about $60, Street Performance is $160.

Just realized we'd discussed the balancer a while back by PM and you and Centaurus both recommended springing for the Street Performance version. I'll put that in my shopping cart.

 

[CDW6212R]

The balancer was not replaced initially, and as far as I know has 250k miles. I'll go ahead and plan to replace it while everything is apart just to be safe.

Do you know what the difference is between the Powerbond 'Premium' and 'Street Performance' balancers is? Premium is about $60, Street Performance is $160.

I opted for the better $160 version, from Rock Auto I believe. It's a nice unit, should never spin(let go). A stock balancer used to be about $75, so call the quality will be the same until you get to the $150 level. For a stock and not to be kept forever engine, the $60 unit isn't a bad choice.

 

[fastpakr]

Sounds good. The cam isn't set up to rev higher than stock, so a stock replacement ought to be adequate. I ordered that and a new Motorcraft cam synchronizer. Hopefully I can get this sorted out over the weekend. Thanks again for all the help!

 

[fastpakr]

Quick update... Haven't had a chance to tear anything apart yet, but did have conversations with the machine shop and with COMP Cams. Both believe at this point that the cam is wrong. This should be fun...

 

[vroomzoomboom]

wait.....wrong? in what way?

 

[fastpakr]

As in the wrong one sent in the box.

 

[vroomzoomboom]

As in the wrong one sent in the box.

......awesome....

 

[fastpakr]

No kidding. Time to pull the front cover and lower intake to confirm ,then I get to fight it out with Amazon and Comp Cams. At this point I don't have the original box and I purchased it in December.