Did I Kill My Bronco?

[deanwats]

1994 EB
351 EFI
Auto Tranny
3" lift
No mods

It was parked for a few months while gas prices soared. I had a coolant hose leak and had to do an emergency repair roadside just prior to parking it. The system was filled with plain water and of course I completely forgot to add antifreeze prior to letting it sit. I'm in NC so freezing temps are very rare.

Long story short, I took it for a drive after sitting and overheated the engine without noticing until the engine died. I was able to get back home, flush out all the rust, etc. The coolant system is fine but I had a rough idle and it smells like I'm running rich. I automatically assumed blown head gasket or worse.

Checked compression:

1 - 145 (200 on repeat)
2 - 160
3 - 180
4 - 170
5 - 180
6 - 170
7 - 155 (170 on repeat)
8 - 155 (190 on repeat)

Plugs looked normal and all cylinders were getting spark,



so checked fuel:

32 psi when running, 38 psi not running with ign on and 12 psi with vacuum disonnected.

Decided to try a tune up. Plugs, wires, cap, rotor, oil, air filter, fuel filter and some fuel injector cleaner. No difference. Tried an overnight treatment of Sea Foam, no help.

Pulled all codes and nothing for KOEO and KOER except 111. Decided to check vacuum. All lines look fine and was pulling ~ 20 Hg". Since no codes, tried replacing TPS and then the IAC valve. Neither helped.

It runs but I still have the rough idle and rich smell. Is she a goner???

[JBfab]

If theres no sign of water in your oil or oil in your water you should be good on the head gasket. Did you put fresh gas in her? If they sit the gas gets water in it because of all the ethonal they use these days. Also did you reset your computer after replacing the tps and iac? Are you sure you have your tps set properly, theres more to it then just putting the screws back in it and plugging it in. Use the search function to find the tps thread on the proper way to install it.

[deanwats]

Originally Posted by JBfab

If theres no sign of water in your oil or oil in your water you should be good on the head gasket. Did you put fresh gas in her? If they sit the gas gets water in it because of all the ethonal they use these days. Also did you reset your computer after replacing the tps and iac? Are you sure you have your tps set properly, theres more to it then just putting the screws back in it and plugging it in. Use the search function to find the tps thread on the proper way to install it.

computer reset but did not know you had to set the tps. I'll do a search. Thanks!

[JerryC]

#5 looks like it could be a little rich or or just slightly oil fouling.

[Kingfish999]

12 PSI fuel pressure whith vacuum off the FPR? isnt it suppose to be like 45 or so? its suppose to be higher than when the vacuum is on. also isnt the fuel pressure suppose to be 35 when everything is normal?

[chairforce1]

Clogged fuel filter? 12 seems really low without vacuum.

[deanwats]

Originally Posted by Kingfish999

12 PSI fuel pressure whith vacuum off the FPR? isnt it suppose to be like 45 or so? its suppose to be higher than when the vacuum is on. also isnt the fuel pressure suppose to be 35 when everything is normal?

That was a typo. It was 42 psi.

[cajunrebel]

Your fuel pressure is highest when there is no vacuum applied to the FPR. The vacuum helps to lower the bypass pressure of the regulator.

[j. r. Nice]

Sounds like either a fuel injector is stuck open, or the ECT sensor crapped out.

[Rustyman]

Most of the time if sensors go bad the ECU will default to values based on a "warm" engine so if anything it would be setting everything leaner.

ECT would throw a code but the Haynes gives you steps to check to see if it's within range.

[deanwats]

Originally Posted by Rustyman

Most of the time if sensors go bad the ECU will default to values based on a "warm" engine so if anything it would be setting everything leaner.

ECT would throw a code but the Haynes gives you steps to check to see if it's within range.

Got a Haynes, I'll check it this weekend. Is there any way to test for a stuck open injector?

[deanwats]

Update:

I'm not one to throw parts at a problem but I'm getting really desperate. The problem still exists and here is everything I've done to date:

Checked compression
Checked spark
Checked fuel pressure
Checked vacuum
Full tune up
Injector cleaner
Sea Foam overnight
Replaced TPS (double checked, installed correctly)
Replaced IAC
Replaced ECT
Replaced injectors ($$$!)

The idle problem still exists and still no KOER or KOEO codes?!?!?

I need some Bronco guru help!

[Kingfish999]

when you did the vacuum yest, was the needel dead steady or was it moving?

[deanwats]

Originally Posted by Kingfish999

when you did the vacuum yest, was the needel dead steady or was it moving?

Honestly, I can't remember. I'll do it again and post.

[deanwats]

Also, I pulled the data after the tune up while idling. Maybe this can help someone help me:

Canst purge ON
ECT (V) 0.6
ECT (F) 192
Engine Speed 724
EVR (%) 0
Fuel PW1 (mS) 3.1
IAC (%) 38
IAT (V) 1.2
IAT (F) 151
Loop status closed
MAP ("Hg) 10.6
O2 Sen1 (V) 0.62
Spark (o) 20
ST FTRM1 (%) 0
Tot (V) 1.4
Tot (F) 138
TP Mode C/T
TPS (V) 1.1
VPWR (V) 14.3
VREF (V) 5.0
VSS (MPH) 0

[bizzle93]

It might be a long shot, but after having my truck in storage, it had similar issues with a rough idle...I found a nest and chewed wires under the air intake (5.8 efi)...after repairing the main harness, it still idled rough but seemed ok at speeds...after troubleshooting like you (parts) it turned out to be another nest in the tailpipe...smelled rich because of the concentrated exhaust...

[j. r. Nice]

Maybe check the EGR. Those make nasty wicked idle when dirty, hooked up wrong or stuck open. If you have constant vacuum hooked to it (like you switched a line) it will do similar to your description.

[deanwats]

Originally Posted by j. r. Nice

Maybe check the EGR. Those make nasty wicked idle when dirty, hooked up wrong or stuck open. If you have constant vacuum hooked to it (like you switched a line) it will do similar to your description.

Would that not throw a code?

[deanwats]

Originally Posted by bizzle93

It might be a long shot, but after having my truck in storage, it had similar issues with a rough idle...I found a nest and chewed wires under the air intake (5.8 efi)...after repairing the main harness, it still idled rough but seemed ok at speeds...after troubleshooting like you (parts) it turned out to be another nest in the tailpipe...smelled rich because of the concentrated exhaust...

You bring up a good point. I'll give the exhaust a once over next weekend. I've been all over the engine compartment and no sign of hitch hikers.

[j. r. Nice]

Originally Posted by deanwats

Would that not throw a code?

Should, but what if it isn't? I'm not sure about the newer OBDs if an open EGR will throw a code or not.

Easy enuff to check.
Start engine.....
Disconnect the vacuum source at the EGR. (shouldnt be any vacuum at idle) See if it makes a difference. If it does, something is causing it to send an incorrect signal to the EGR.

Connect a known vacuum source to the EGR and see if it makes a difference.
If it does, the EGR is probably working "ok".

There are other tests for the EGR and sensor in a Haynes manual if this looks like it might be part of the problem. Often, it requires a hand held vacuum pump.