What do you think a good next step is?

Remove EGR valve and sensor and clean all the passages?

Replace fuel filter?

Thanks

 

Did you have a detonation problem before the MAF swap? You say it's always been set at 8deg advance so that's suspicious. You will have to verify the metal parts of the air injection system are not rusted out.. very possible with a vehicle this age. My '89 became very detonation prone when this system failed, and I couldn't cure it until the problem was found. There is a metal pipe across the back of the heads, you may have to remove it or at least get in there with a small mirror and inspect it.. this was the problem on my truck. A motor in good condition will pass emissions with this air system removed, so it's not needed unless you have visual inspections for all OEM smog equipment.

 

No pinging before the MAF conversion. But then the knock detector was hooked up and working. It must cover a multitude of sins.

I'll check out those tubes and the air pump and air hoses today and do an R & R if needed this weekend.

We have visual inspections of the emissions system. It must be OEM. My Volvo got bounced because of the wrong type of gas cap. I replaced the OEM with a locking cap. It held the pressure, but the inspector made me replace it.

Thank you!

 

I checked every sensor and actuator. Almost all function to spec. I removed and cleaned the EGR valve and plenum port. All of the thermactor pipes and hoses are in perfect shape, no rust or leaks. It was a job and a half to pull out and replace the smog tubing on the back of the engine along with the diverter valve!

I replaced two questionable vacuum lines that held vacuum, but appeared slightly clogged.

The first of my two issues is that the TPS valve seemed had a reading of about .897vdc closed rather than .901vdc, a difference of .004vdc. Open throttle was about .001vdc out. I am not worried about that small of a variation. The voltage rose smoothly as the throttle was opened.

The second issue is with the TAB valve. It checks out ok (vacuum; solenoid; vacuum tubing; wiring; port change) but the PCM keeps it open at idle. I always thought the it bypassed the thermactor air thru the check valve after 3-5 minutes of idle. I removed the vacuum and the thermactor air was dumped from the system, the A/F read slightly richer (still lean) and it pinged at 10*.

Now I have reset the timing back to 7.5*. I reconnected the TAB vacuum. I have a system that does not ping and runs on the lean side. It accelerates smoother and quicker that the SD system. I have purchased an IST Air Adjuster. I should get it by Friday. That should make it a bit richer and eliminate the ping.

 

A few thoughts...

The problems that I can think of associated with retarded timing is loss of power and hotter exhaust gas temperatures.

If you have problems with #8 cylinder, you need to relocate the PCV or eliminate it and use a draft tube. The factory location of the PCV is know to destroy the #8 piston, rob, bearing etc.

Since you have MAS, a vacuum leak will lean out the motor. With SD, fuel is added via the MAP sensor to match the air. So, a vacuum leak may very well be causing the lean condition that you now have that was not so problematic with the SD system that was seemingly running OK. I suggest a smoke test.

Instead of performing visual inspections and cleaning off stuff you would probably be better off temporarily eliminating various systems all together...ie AIR, EGR, PCV etc.

What did you use to test the TPS?

What is the IST Air Adjuster kit and how does it richen the mixture?

 

I put an air/oil separator in the PVC line. I hope that will catch most/all of the liquid that passes thru to the #8 cylinder. The #8 plug when I changed it last was the only one with any carbon at all on it. For 12 years and 50K miles on the plugs, I was surprised with how clean it was.

I have driven only 100 miles with the timing at 7.5* and only 50 miles more before I reset the timing to 10* and install and tune the Air Adjuster. My truck is not a daily driver. It is my baby!

When the motor was SD two weeks ago, the idle was a rock solid 650rpm. It is still 650 and rock solid. Since then I have tested every diaphragm, line, reservoir, actuator, solenoid, and fitting with a vacuum pump and bleed-down test. I disconnected every vacuum apparatus but the brakes and the cruise control. None of this changed the pinging threshold. I used brake cleaner around every gasket interface with no impact on idle speed or quality.

When I said that two vacuum lines appeared slightly clogged, I did not mean visually, but rather from my testing. Those two lines did not leak down after two minutes, but took a more pumping than expected to evacuate the lines. I find it almost impossible to visually inspect the vacuum system in these vehicles. The lines are all hidden in convoluted tubing! It was a mistake to use the word "appeared". I should have said "the tests indicated".

The only devices, gaskets, tubing, or potential areas of leakage not thoroughly checked are the brake booster and the cruise control.

According to my '89 F/E series shop manuals the lowest idle value possible for the SD is 652rpm. My truck was right there. A leak in an SD motor raises the idle value. That is a strong hint that 2 weeks ago the motor had minimal leakage.

I used a KOEO test using my good DVM and probing the insulation on the wires indicated on my Ford shop wiring diagrams. My son moved the pedal at my direction. I used that same meter to check resistance or voltage on every sensor.

It appears to be an amplifier that can scale the MAF sensor voltage to indicate to the PCM an increase or decrease of up to four fold of measured air. It can be used to fine tune the A/F ratio by making the PCM think there is more or less air than is extant.

http://www.mass-air.com/Products.htm

 

What about all the carbon particulate that passes through the PCV that gets dumped down #8 cylinder? Oil seperator or not, you are better off relocating the PCV to the top of the plenum. Ford released a TSB about this. If your truck is your baby, this is what you ought to do.

A volt meter is only usefull for testing the throttle closed and WOT value of the TPS. Anything between those 2 values you need an oscilloscope to get usefull readings...same goes for any potentiometer...reason being that the digital display in a DVM is not quick enough to catch an irregularity in the reading or any bad spot (TPS or any other sensor for that matter). Same goes for the ballistics in an analog meter...they are too slow even though analog is theoretically real time. With an oscilloscope, not matter how fast you move the throttle and no matter how minute the bad spot, it will give you real time data and you will see the bad spot.

As far as you testing every potential vacuum leak with brake cleaner and a vacuum pump aside from the break booster and cruise control servo, how did you check the underside of the intake plenum? Due to the content of those vapors, the idle speed wont raise if a leak is present even if it's SD. Depending on the size of the leak, it may cause other problems though.

 

EDIT: I meant to say the underside of the intake manifold.

 

It'll happen at the next service. At this point I am not too worried as my filter is 3-5 microns. Eliminating the oil before it burns should eliminate most of the dry carbon residue. I thought it was gas and suspended oil droplets in the in the PCV system, not suspended solids. I don't have the strength to remove the plenum myself. That's why it has taken me since the last week of December to install the MAF stuff and double check everything.

I've read what you have written about this before. I've looked for that TSB and can't find it. But I did find a page about it at the Ford Fuel injection site.

So? I checked the full open and full closed position and seveal spots in between as my son sloowly manipulated the pedal in between. For me to pull out my "silly"scope for this is overkill. It pings at full open somtimes and the TPS is good there.

I spayed the passenger side of the plenum split and the block/intake join as best I could. It is difficult to spray there and it may not be perfect. I found the vacuum leak there, on the passanger side of the plenum split, with brake cleaner a year ago. I went looking for a vacuum leak because the idle speed went up. I've had three leaks in recent times. All three resulted in a higher idle speed.

 

So? So you did not effectively test anything other than closed throttle and WOT. All those readings for the spots in between are meaningless, whether or not it pings at WOT.

Even though the block/manifold joint may be difficult to spray, I was talking about the UNDERSIDE of the manifold, as in the spot that seals the manifold from crankcase vapors and it is impossible to see or spray from the outside. Leaking crankcase vapors into the intake is not the same as leaking air into the intake, and you will not necessarily get a high idle. The only thing that I know of that will find that leak is a smoke test.

 

I don't recall if it was mentioned here but what computer are you running with this system? Are you running 2 O2 sensors or 1?

 

Paul,

I am running C3W, the one recommended by the tech guy at Ford Racing. He gave me the part number and I got it at Valley Mustang here in L.A. The Ford techie said it was the same one that was in the M9000-T51 kit. It is the same as a '93 Mustang LX 302 non-H.O.

I have one HEGO that I have run to both R & L HEGO PCM connections.

Thank you,

 

So, have you rewired the injectors for sequential injection right? I don't recall any of the 5.0 mustangs ever being non-HO...

 

Paul,

I rewired the injectors to match the Mustang wiring diagram...

I'll check out the the firing order of a non-H.O. Mustang 5.0, if there is such a thing.

Thanks!

 

Oops!

Good catch Paul!

They changed the firing order on the 302 in cars in the early '80s.

I am swapping four wires tomorrow afternoon.

THANK YOU!