wont start

explorer98 · Sep 18, 2014

I got a good one. My 5.0 transplant in my 98 explorer sport wont start. I can get it to start every once in a while, but when it does start it runs really rough at idle and when you give it any throttle it starts spuddering and backfires. Sometimes when I try starting it, it will backfire. This is what happened, I was at a stop light and the rpms dropped and it started running like crap. It would barley move and it was chugging and backfiring. I keep getting p0353 and p0354 codes. I've replaced the coils, plugs, airidlecontrol, intake gaskets both upper and lower. Also this engine only has 4000 miles on it, oh and I readjusted the valves. I have roller rockers on it. If any buddy has any suggestions im open for anything. :beer:

RonD · Sep 18, 2014

Not for nothing....but can you check fuel pressure, I know the codes are for coil 3 and 4 issues.
50psi key/engine off, 65psi engine running(assuming '98 returnless fuel system)

I assume you have two coil packs, and #3 and #4 are on different packs, so it would be odd to get those two codes unless the problem was in the wiring to the coil or the PCM(computer).

But 3 and 4 are right next to each other on the fuel rail, so.............

The PCM reads feedback from the spark plug via the coil so these codes can be set from misfires.

And the no start reads like either no spark at all or no fuel, not a 2 cylinder issue, which, on a V8, would startup easily just run really rough.

You should read fuel pressure but try adding fuel to the intake, gas or starting fluid, and see if it fires up then dies, that would be a fuel issue for sure.

And since it happened while running I would lean towards fuel issue, electric usually fails when powered up, unless it was heated up while running the electrics tend to work, then fail at next power up cycle

explorer98 · Sep 18, 2014

I'll try that, I know when I take the cap off on the fuel rail and press down the valve fuel squirts out. I know the fuel relay is good. When this all started their was two misfires that came up but it hasn't showed up again.

RonD · Sep 18, 2014

It should squirt out along way, 60psi is TWICE the pressure in a tire.

Pull out a spark plug after cranking and a no start, it should be wet with fuel, not a little, but wet.
If it is then use a lighter or match and light it, it should burn easily, if not you have water in the gas tank.
Did you get gas just before this happened?

If you have a timing light hook it up and crank engine, make sure #1 is sparking steadily and near TDC every time, so not jumping around.

And I know it is correct, but just check the firing order one more time, lol, I goof that up all the time and would swear it is right.

The coils are controlled by the PCM grounding them, just like single coils.
The codes(p0353/354) can also mean these Ground wires are shorted to power, so follow the wiring back to the PCM looking for any spots they may have rubbed against something.
Or pull of one of the coil connectors, put a test light to #3 or #4 coil wire(going to PCM) and then hook the other lead on test light to ground, turn on key and move wires around and watch for the light to come on.

explorer98 · Sep 18, 2014

I did notice that when I pulled number one spark plug it was wet.

explorer98 · Sep 19, 2014

Update I tried the starting fluid and it wont start with it so it must be electrical. I was going to do a compression test but I ended up frying my starter or the solenoid so have to wait on that. Yes it does have a return line for the fuel so the pressure should be way less than 60psi. I cant remember what it is but didn't test it do to the starting fluid not working. What about the TPS can that cause problems when they start to go bad?

RonD · Sep 19, 2014

No on the TPS, it can't cause a no start.

Only sensor that can cause a no start is the CKP(crank position) sensor, it is behind the main pulley, but these rarely fail, and would for sure turn on CEL if there was a problem.

The '98 Explorer has Type B PATS, which allows the starter to work but disables spark..............

What year is the 5.0l and computer?

explorer98 · Sep 20, 2014

the 5.0 and computer are out of a 97 mercury mountianeer

RonD · Sep 20, 2014

Mountaineer didn't get PATS until '98 so that shouldn't be the issue

explorer98 · Sep 20, 2014

I guess i'll just keep plugging away and see what I can find. Just about to give up and put it up for sale.

explorer98 · Sep 27, 2014

update on my problem. Got my starter back in and was able to do a compression test and found that #2 cylinder is dead. Anybody know what I can do to fix this? :beer:

RonD · Sep 27, 2014

Start by pulling the valve cover off #2 side, remove all spark plugs then manually turn engine and see if both #2 valves are closing all the way, i.e. their height compared to the other valves on that side.
Then you will be pulling the heads, checking the valves is just an FYI, can't fix anything from there.
It could be a rocker is holding it open, but with hydraulic lifters that is not likely.
Hopefully you just have a bad valve not a hole in the piston.

explorer98 · Sep 27, 2014

I'll do that and keep this updated. Also was told it could be a broken valve spring. I'll find out tomorrow. Thanks for the help Ron D.

wont start

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