98/2000 ohv swap

98/2000 ohv swap with answers

Well, I never expected to be on the modified side of this forum, but swaping a 98 into a 2000 seems like a non-stock situation to me. I had a mechanic (shade tree or shad-y depending on viewpoint) swap this 98 with 65K into my 2000 explorer.

original vin#1FMZU72X8YZC34954 with eng from vin#1FMZU34X7WUB78005; a 98 explorer w/65K.

He left the same computer. Truck flares, stalls regularly, bucks and kicks occassionally below 1500rpm. Runs like it has 5 1/2 cylinders otherwise. All plugs firing. Behaved better before replacing O2 sensors. Ran like this for many miles without ENG light coming on. Then threw Cam-pos sensor, and lean banks codes after bucking and kicking and stalling.

Reading here I see folk talking about 98 fuel feed sys being different from 2000 sys. But, where to go from here? Checked a load of sensors and everything seems to be in order.

My current mechanic is scratching his head. The 98 cam-pos sensor had 3 wire, the 2000 had 2. We installed a 2 wire sensor that matched the harnes plug and the cam-pos code went out. Solved nothing. Truck ran better when the can-pos sensor was unplugged and the O2's were reading bad.

11/23/2011 all issues solved. Read the rest of this thread if you want to see some of the diagnostic paths that were taken.

Here was the result of MONTHS of working on this truck.
The idle issue: was stumbling and flaring. Turned out to be primarily an EGR valve missing a gasket to the EGR tube. Std vacuum leak.

The stumbling and bucking: primarily bad wires, cracked plugs, poorly connected fuel injector

The lack of tempo when accelerating and fumbling below 2000rpm. Camshaft sychronizer and postiong sensor. Turns out the 2000 employs a hall effect sychronizer with a two wire magnetic sensor. The 98 motor had a variable reluctance synchronizer and three wire sensor. The two wire synch has a 1/4" vane at the top and the three wire systm has a 180degree vane. Not compatible though you can park the wrong sensor atop the synhronizer.

Truck now runs like new in all respects.
Thanks to all who stuck with me on this one.

fuel pressure regulator

The 1998 has the fuel pressure regulator (FPR) on the fuel rail. As the vacuum changes the fuel pressure changes. Maximum fuel pressure is at WOT (40 to 50psi) and minimum fuel pressure is at idle (30 to 45 psi).

The 2000 has the fuel pressure regulator in the fuel tank and a fuel pressure damper on the fuel rail. The fuel pressure stays fairly constant (> 60 psi).

If you used the 2000 fuel rail then there is no fuel pressure regulation which will adversely affect the air/fuel ratio.

I think there are engine wiring harness differences between 1998 and 2000. I don't know if the synchronizer wiring is the only difference. One member corrected his problems by using the 1998 engine wiring harness.

did you just swap over the engine, bare long block or everything with it?

Thanks for the replies.

I believe the mech kept the same wiring harness from the 2K engine because the cam-pos sensor plug did not fit the 98 engine.

Consdidering the fuel pressure issues, I'm surprised the truck runs at all. I'll pass all this info onto my current mechanic and see what results. Meanwhile it's a serious dog to drive.

misread original post

I just realized I misread your original post. Your mechanic put a 1998 engine into your 2000, not a 2000 engine into a 1998. I wonder what he did about the fuel pressure regulator on the 1998.

Hey!~ I wonder too!!!! Not sure how much and what parts he carried over from the 2000. My mechanic blew out of here with the hurricane (property down south I think) so no more news until sometime next week.

While waiting for my mechanic to return I looked under the hood. There is a vacuum actuator on the fuel rail. This means to me that I have the 98 rail. The symtoms are consistent with a 2000 computer thinking it has 60PSI constant fuel pressure when actually the FP is dropping to 30 near idle. AT low rpm in higher gears the FP is too low to keep up with demand and the faultering begins.

Here is the question. Is there a way to simply jack the vacuum gauge so it leaves the FP near 60psi all the time. The 2000 computer is looking for that anyway.

And...are the fuel injectors the same for the two fuel rail systems, or are there different injectors for 98 than 2000? With 60psi fuel at idle, will the 98 injectors respond to the 2000 computer properly?

damper or regulator?

The 1998 has a fuel pressure regulator (FPR) mounted on the fuel rail and the 2000 has a fuel pressure damper mounted on the fuel rail. Both would have a vacuum connection. The FPR has a port to allow excess fuel to return to the tank. If your mechanic used the FPR then the return port would have to be plugged some way. Here's a photo of a typical FPR.

Thanks 2000, the thing on this rail looks more like a pancake. I'll take another look to see if it has a return line. Either way, do you know if the injectors are compatible?

injectors

The injectors should be the same unless one of the engines was originally in a vehicle sold in California and the other wasn't.

couldnt you just install the 2000 fuel rail/upper intake on the 98 motor?

I havn't had a 98 apart myself, but it does seem like a simple solution.

Yes, well, I think that is a very good idea...but I am not a mechanic. I understand that the pump and or other parts are in the tank on the 2000, and exterior on the 98. Is changing the fuel rail not invoving the pump and tank parts? I'm hoping my mechanic will see the options. His cell is down from Irene and we get one call in every day or so. I no longer have any of the 2000 parts, but have no issue with getting another rail from the yard or wherever.

Will definitely let everyone know how this irons out.

Finally got a chance to look into this fuel pressure issue. The rail is providing just under 70psi constant. Idles down and stalls, or flares up over 2Krpm like a seesaw. Runs okay over 2krpm. There is a vacuum controller on the fuel rail...but removing the vacuum hose produced no effect at all.

Truck ran better before I repaced the bad O2 on the left bank. Still had idle problems, but didn't kick and die under 1500rpm under load.

Any more ideas?

The "vacuum controller" on the fuel rail is[or should be] a pressure damper...It is there to smooth the pulses of the fuel going to the injectors... And it has no effect on the fuel pressure..

Frankly the "seesaw" idle effect you describe sounds either like the IAC not functioning properly or a vacuum leak...

Your fuel pressure is good as the returnless system delivers 65-72 psi constant...I would concentrate on verifying the vacuum lines, the air tube from the MAF unit to the tb, and finally using carb cleaner or other fluids to verify a vacuum leak around the brake booster fitting, the upper intake, or the egr porting...

Ranger,

You and Ford are on the same track. I paid $98 for a diagnostic since my mechanic just couldn't nail this thing down. They came up with 171,174, 303,305,306,340 codes. Said vacuum leaks. Also threw in cam-pos may be off, though I don't believe my previous mechanic pulled it from the existing engine. And, before changing the O2sens and re-connecting the evap vac line (which he had pulled and plugged presumably in search of leaks) the truck ran like a race horse. Idled badly, but ran smooth and strong. New mech says he's got access to a smoke machine for this vac leak hunt.

update

No progress. Bought a 2002 Durango just to keep rolling. Meanwhile, no vacuum leaks have been detected. Cleaned the MAF and IAC which was quite dirty. Minor improvement, idle seems to be better, but still hops around. Someone said cracked plug or plug cap which I will be looking into in the days ahead. Anybody know how far out of time a cam-sync can be and what it will do to the way the engine runs? I just find the bucking hard to square with being off time. There are no adjustments on the cam-pos so the only way it can be off is geared in wrong?

ongoing struggle

Searched plug wires and plugs for failure points. Found seriously cracked plug wire and cracked plug. Got to be part of the problem, no? Repaced the plugs and the wires. No improvement. Switched plug one and three around at the coil pack and it ran the same! What is going on here?

Anybody know the symptoms of sychronizer being advanced or retarded? Could the mech have put it in wrong and get these symptoms?

Okay, so I investigated the coil/plug wiring set up and discovered that the freakn' mechanic had the firing order wrong! That corrected now the engine runs better, but still feels like one cyclinder isn't quite there. I also believe I've found a vac leak under the EGR vacum actuator. The pipe is covered with a heat shield wrap of some kind making it hard to get at. That work begins tomorrow morning.

EGR valve to tube gasket was missing. Solved the idle issues. Now it looks like it's all about the sycnronizer and campos sensor. This was an eng swap. 98 4.0 into a 2000X that had a 4.0. Turns out the synchronizer are not the same year to year. The sensor for the 2000 is a three wire, and the 98 is a two wire. Looking now into whether a 2000 synchronizer can mate to th 98 block. If so, I may be in the clear. If not, the junkyard calls.

If anybody knows, please pipe in!