Catalytic Converter and Engine Problem

[new2fordbronco]

I bought a 92 Bronco 6 months ago. It has 114000 miles on it and ran great. I was driving it on a 240 mile round trip over the weekend all highway miles when my cat overheated and actually caught my tranny on fire. My engine is 5.8 and before the tranny caught fire, it started losing power (cutting out, missing, and decelerating.). The bronco stopped on the roadside and when I stopped, I realized the tranny was on fire.

To make a long story short, I drilled 4 - 1/2 inch holes in the cat to allow it to breathe and it ran okay coming, was about 2:30 a.m. I drove for 20 miles and the last 5 engine started losing power again, cutting out, etc. I got her home and cut the cat off and straight piped it to the rear of the bronco. Now my engine is running very eratic. Has good idle but upon acceleration, it cuts out, backfires, and will not climb a hill.

Check Engine light is on and it has the following codes - 56 which my machine doesn't have data for but googled and says mass air flow. Also getting another mass airflow or trans temp sensor out of range; 93 - TPS voltage low or cruise clutch solenoid, EGR valve erratic, has insufficient flow; O2 sensor reading lean; fuel pump solenoid voltage low. I cleared codes and still get the EGR valve, TPS voltage low, and MAF sensor faults.

I replaced air filter, plugs, wires, distributor cap, rotor button, and ignition coil today because of this was severely worn out. Also tried to seafoam the engine and didn't get any smoke coming from the pipes. Is it possible that my problem is the intake is stopped up? Or would it be where the transmission caught fire.

This thing is kicking my butt. b-( Thanks for the help on this.

 

[bidibronco]

Once you take the cat out it'll mess which the O2 sensor which will start messing with everything else. If I'm not mistaken there's a breather tube on your cat that ran somewhere (can't remember where). That may be on a different modle so don't hold that one to me. I would put a new cat system back on it and let it do it's job for the O2's so it doesn't start hurting everything else. My buddy let his O2 go bad and when he finally got around to fixing that he found out his MAF was bad and something else. Now that I think about it, a 92 wouldn't have MAF? A 92 should have Speed Density unless it's been converted but with the double didget (spelling?) codes sounds more like EEC IV. I would deffinatly keep it off the road and throw a cat on it. Hopefully someone who knows more about this than I do will chime in.

 

[BroncoJoe19]

I bought a 92 Bronco 6 months ago. My engine is 5.8
Check Engine light is on and it has the following codes - 56 <snip>

My sources say that a code 56 is ONLY for the 4.9L 6 cyl.

You may want to try pulling codes again.

Try reading this tutorial, see if it sheds light on something that you may have done wrong in pulling codes.

http://broncozone.com/forums/index.php?s=&...ost&p=74581

joe

 

[new2fordbronco]

My sources say that a code 56 is ONLY for the 4.9L 6 cyl.You may want to try pulling codes again.

Try reading this tutorial, see if it sheds light on something that you may have done wrong in pulling codes.

http://broncozone.com/forums/index.php?s=&...ost&p=74581

joe

That's what I was thinking. I am using a GM Tech1 as the majority of the autos that I work on is GM. It has the programming for Ford and Chrysler as well though. I am not sure why it gives me the code, it tells me 56 and no data available. I am kind of thinking that the EEC (????) has failed on it though because it repeatedly tells me something is different. I pulled codes today for EGR failure, MAP Sensor vacuum disconnected or damaged, and Thermactor system failure. I can understand the thermactor system failure as I don't have cat on it so emissions are shot. I am almost positive that a stopped up cat wouldn't cause all sensors to fail or act stupidly. The engine smells like it is overloading with gas and the only time that I have issues with it running is during acceleration. Once I reach 2500 rpm the engine smooths out and runs properly. I cannot run below 2500 rpm while climbing a hill though, even it requires to me downshift to 1st gear. I am not so sure that perhaps whenever the transmission caught on fire if it could have possibly shorted wires going to EEC and is causing a cataclysmic chain of events which in turn is causing my engine to run very poorly.

I did pull intake off today and cleaned it and in place the ports were over 1/4 thick with carbon. I will put it back together tomorrow after I get my new intake gasket in. Also, I did replace the throttle position sensor because every single time that I ran KOEO test on the bronco that sensor showed low voltage. In my experience though, I have never seen a tps cause an engine to miss on acceleration or even die.

I did wonder about the mass airflow sensor, being as I couldn't find one when looking for it under the hood.

Thanks for the help and hopefully I will report back with good news tomorrow. /emoticons/[email protected] 2x" width="20" height="20" />

 

[BroncoJoe19]

Seems to me that you know more about this stuff than I; so good luck

I noted earlier that a number of your sensors responded with low voltage.

I seem to recall that a lot of them get their power from the PCM. You might want to trace back and see if the PCM has a good ground, and that it is getting a clean 12 volts. Isn't there a power relay to the PCM?

I'm in over my head here, so don't take anything I say as gospel at this point, but if something makes sense, I hope it helps.

joe

 

[BroncoJoe19]

Seems to me that you know more about this stuff than I; so good luck
I noted earlier that a number of your sensors responded with low voltage.

I seem to recall that a lot of them get their power from the PCM. You might want to trace back and see if the PCM has a good ground, and that it is getting a clean 12 volts. Isn't there a power relay to the PCM?

I'm in over my head here, so don't take anything I say as gospel at this point, but if something makes sense, I hope it helps.

joe

Here is a list of grounds for a '92 - '96 bronc

I took a look in my Haynes manual.

They list 10 separate grounds... A-J.

A. Starter mounting bolt

B. Right front of Engine compartment near the battery

C. Lower left front of engine

D. Right front of engine compartment on upper radiator support.

E. Left front of engine compartment Upper radiator support

F. Bottom of cowl panel

G. Rear of left fender apron

H. Behind bottom of right cowl panel

I. Left rear corner of cargo area near rear lamp assembly

J. Under center rear of vehicle on rear cross member.

According to the Haynes manual the PCM gets its ground at ground B.

Wouldn't it be great if it were as simple as that?

Good luck

joe

 

[new2fordbronco]

Here is a list of grounds for a '92 - '96 bronc
I took a look in my Haynes manual.

They list 10 separate grounds... A-J.

A. Starter mounting bolt

B. Right front of Engine compartment near the battery

C. Lower left front of engine

D. Right front of engine compartment on upper radiator support.

E. Left front of engine compartment Upper radiator support

F. Bottom of cowl panel

G. Rear of left fender apron

H. Behind bottom of right cowl panel

I. Left rear corner of cargo area near rear lamp assembly

J. Under center rear of vehicle on rear cross member.

According to the Haynes manual the PCM gets its ground at ground B.

Wouldn't it be great if it were as simple as that?

Good luck

joe

It was a ground or should I say grounds. 4 of the wires were broken and one was in very bad shape, I assume salt and wear had a lot to contribute plus the fire underneath the vehicle didn't help. I completely never thought to check that out. Thanks so much for your help. I was thinking about the fire (wires burning or shorting) to start at one of the simplest problems.

Thanks again.

Scott

 

[BroncoJoe19]

It was a ground or should I say grounds. 4 of the wires were broken and one was in very bad shape, I assume salt and wear had a lot to contribute plus the fire underneath the vehicle didn't help. I completely never thought to check that out. Thanks so much for your help. I was thinking about the fire (wires burning or shorting) to start at one of the simplest problems.
Thanks again.

Scott

Scott,

Thanks for posting the solution.

I'm glad that you are as good a mechanic as you are, or this would have been a real hair puller!

Enjoy the upcoming weekend!

joe