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New 300-6 Engine will not go above 2000 RPM

Kaajot

Micro Machine Manager
Hi all-

Mechanic has the new 300-6 engine painted, installed, etc. Everything is back together except the dip stick (it's plugged, need to find my original dip stick for this year engine and install it at the 500 mile oil change).

Apparently it runs strong and solid, but after the first two minutes he couldn't get it to go over 2000 RPM.

Also, ODB1 Codes only come through with old school reader or papercliip. All of the mechanic's pro-readers (snap-on, etc) several types and brands cannot pull the computer codes like it used to.

That's making me consider the wiring harness or the computer.

And if there is some kind of "reboot" process to the engine, he probably didn't do that. A friend in Arkansas recommended that to me 6 years ago, wondering if anyone has ever heard of any "reboot procedure" for getting the engine and computer to sink up with pressures, fluids, throttle rpms, etc.
 

dustybumpers

don't play well w others
Check pcm grounds, if the scanner wont connect

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Kaajot

Micro Machine Manager
Check pcm grounds, if the scanner wont connect

Sent from my SM-N960U using Tapatalk

That was one of my things I thought. I literally listed PCM, MAP/TPS (which was part of the fight with the old engine), wiring harness FUBAR'd or lastly the Transmission being boondoggled and needing a new one of those, but he inspected the flex plate and changed the filter. Everything looked fantastic in the transmission and clean fluid, no shavings, etc.

Mainly think its a bad wiring harness, or something with the PCM (we replaced in 2017, sad if it's gone bad again).

Can it just be a wiring ground to the PCM that can be repaired (spliced?) and still have a good PCM?
 

dustybumpers

don't play well w others
Ground runs from pcm to the hood hinge driver side. There is another ground on header core support on the inside behind the driver headlight. INSIDE
3rd ground is for fuel injectors, and comes right off the neg battery cable.

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Kaajot

Micro Machine Manager
Ground runs from pcm to the hood hinge driver side. There is another ground on header core support on the inside behind the driver headlight. INSIDE
3rd ground is for fuel injectors, and comes right off the neg battery cable.

Sent from my SM-N960U using Tapatalk

Thanks Dusty!

I've seen the one on the hood hinge. I have had issues at the driver headlight wiring bundle with my led (falling apart/getting yanked because a support was not set properly by the washer fluid reservoir) and we know about the fuel injectors neg battery cable one too, that's the one that originally was not grounded I believe that we found (and fixed all the rough hesitation we had).

He said Engine has no hesitation, etc. Runs strong, sounds amazing. Just can't get past 2000 RPM. This'll be good info.

I'm taking a snap shot of this to Keith, just got off the phone with him -- he's the mechanic & operator/owner. He'll be thrilled to have this info.
 

dustybumpers

don't play well w others
Check fuel pressure. I forget what year the truck is85-89 had a 2 pump system. Low pressure tank, high pressure rail. 90 to 97 has a high pressure pump each tank.
Also in the 85-89 trucks the FDM
( fuel delivery module)
By the fuel pump takes a crap, and shuts down fuel pressure.

The newer trucks have a issue with pressure regulator. If you pull the vacuum hose off, and the idle raises, or it pumps gas out, replace it

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Kaajot

Micro Machine Manager
Check fuel pressure. I forget what year the truck is85-89 had a 2 pump system. Low pressure tank, high pressure rail. 90 to 97 has a high pressure pump each tank.
Also in the 85-89 trucks the FDM
( fuel delivery module)
By the fuel pump takes a crap, and shuts down fuel pressure.

The newer trucks have a issue with pressure regulator. If you pull the vacuum hose off, and the idle raises, or it pumps gas out, replace it

Sent from my SM-N960U using Tapatalk

I'll send that one to Keith too, but we've talked about it and he checked fuel pressure. I had to remind him the truck has two fuel pumps. Didn't realize it's a high pressure pump in each tank though, that's good to know.

No FDM I believe, have researched that since this is a 1992 and we were troubleshooting the truck a year ago with the bad engine, etc.

Pressure Regulator on a 1992? Is it the Idle Air Controller (IAC) Solenoid there by the EGR Valve? We've pulled that off before to see if there's a change in the engine. Normally, none. Definitely never had gas pour out there.
 

Kaajot

Micro Machine Manager
Update: EGR Valve is suspected to have caused the loss of RPM power with both the bad engine and the new engine. Ordered a new one from Rock Auto.

Old one was new and installed on the old engine for 4.5 years and did take all the abuse of all the problems I've reported for the last 4 years, including blowback/blow by, electrical shorts killing the TPS and 4 MAPS, and a lot of valve/cat converter/egr tube/injector repairs (all new parts now since 2017).

That and a rock'n bad engine on bad motor mounts, I guess I was going to have to pay to play. Hoping this is the last fix needed to get this thing driving. I've been needing to grab two new tires all year and the truck has just taken my money every single time since 2015 and all my mobility and time to get to anything worth while.


**** Lamentation about not having a working vehicle for 10 weeks ****

The 1983 F-700 is "repaired" but has a grinding hard brake on back left wheels, need to blow that open and inspect. It's hydraulic leak at front left can't be repaired without a new steering gear, so I'm going to have to spend $$$ to get that beastly thing. We've dumped $150 into trying to repair its sleeve and seal, no dice.

Master Cylinder and Brake Boost do appear to be good, and no more leaks. Repaired window in door, stero system, antenna, and most of the instrument cluster. I'll have to jump around and take pictures of what we worked on and replaced.

It has one nagging issue and I bought a wiring diagram to figure it out. It had a short on the drive up in Georgia where I broke down and repaired the starter solenoid. The smoke rose from the instrument cluster. We found the burns on the back of the cluster there and repaired it, but the main fuel gauge on the instrument cluster will not read. Secondary fuel system does read (put a new sending unit in it). I've a new gauge there to install because the secondary gauge for the aux fuel tank its wired to has no illumination, it's pretty old. Cost like $18 for a new one, just have to wire some power to the illuminator tied to the lights.

*** End Lamenting ****

I'll let you know if the EGR Valve fixes the F-150!
 
Last edited:

Kaajot

Micro Machine Manager
Not EGR Valve

So, mechanic wasn't clear and I bought a new EGR Valve part that's going back to Rock Auto with the starter he also determined he didn't actually need after I ordered it.

He is now saying TPS, but we're having some issues figuring out if we've been installing the wrong Throttle Position Sensor.

This is a 1992 F-150 4.9l E4OD Automatic Vin Y transmission vehicle.

It does have that "throttle body spacer" which believe Dusty said to eliminate and the mechanic didn't bother asking me while I was putting out personal fires, so it probably got swapped over.

That said, the current TPS installed is F2TF9B989AA, ordered 3 days shy of a year ago from Rock Auto. However, order was for F2TZ, not F2TF. Motorcraft part.

Should I be looking at a different TPS like E9TF9B989BA, also available for my truck model off Rock Auto?

Advance Auto Parts didn't recommend that option. They recommended F2TF.

And could a faulty TPS inhibit the CMD from sending codes to a reader on the ODB1? I don't buy that, but mechanic says he traced the grounds and had no indication of a break (or resistance I hope he tested that for as well, but I'm not there to do my own checks).
 

Kaajot

Micro Machine Manager
World's tiniest violin here...

So, besides a TPS, the SMOG PUMP's Bearings lasted 23 months and I bought from NAPA, not Advance Auto Parts. Advance has a limited lifetime warranty, NAPA was same price if I used the discount code at Advance for 25% off, and a day to receive instead of 3-4, but that's where the first one came and it's only a 12 month warranty/18K miles.

So, waiting on smog pump as well.

This is ground hog day, but I think it's those motor mounts and evap leak on a bad engine that did everything in. With the new motor and new motor mounts, I'm really hoping the smog and tps and map and everything actually stop breaking.

Still going to get a new multimeter (mine was stolen) and shoot some resistance on the computer on my own if we get this running. I have a hard time believing the codes only can be pulled old style (used to be able to come through the machine in 2017 and even 2018). Haven't been able to pull electronic codes through an advanced laptop reader since then, just read the flashes and manually extract codes.
 

Kaajot

Micro Machine Manager
I've got the F-150 back, but it's throwing codes 637 and 628 or 638, think 628. Transmission related.

RPMs will get up there, can get up to 65 so far, no problems, but it shifts a little hard in the lower gears and downspeeds quickly instead of "coasting" without applied brakes.

The biggest problem, and this has been a "feature" since 2017, yet we have a brand new engine and all kinds of new parts now on there including a smog pump, is that going to reverse kills the engine. Stalls it out. I used to be able to power through it with a high rev on rpm, but it's bad. It literally kills the engine.

Also, found mechanic did not inspect the grounding points recommended previously except the one closest to the odb1 plug (the ground at the hood) but he had to remove the hood, so maybe he was looking at it enough.

We inspected the ground at the driver side headlight. It was green as could be and needs new eyelet installed and the copper cut back to non-green copper wiring. There are two grounds, a smaller black and a larger black ground on that part of the frame. I'll be fixing that. I mention this because both snap on and an older card reader could not get the KOEO and KOER codes, nor could it clear the codes.
 
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