Bought a 95 exteded cab truck with issues

[Ackattack]

So I bought a 1995 extended cab 2wd tonight that has some issues that I will need to get figured out. Its a 305 with a 5 speed. The fuel pump is new.

Apparently the truck was having some issues with not running real well and a periodic severe loss of power. The PO thought it was a clogged catylitic converter, and cut the front of the cat off, and said he heard loose clunking material in there. He got fed up with it, and sold it to me.

So currently the y-pipe is cut right between where it y's together and the cat. Its loud (of course) and would kind of run, almost die, then run OK, then not much power, and smells rich.

I don't have the truck home yet (picking it up on Wednesday), but I'm thinking that the oxygen sensor is currently showing lean since the y-pipe is cut, there for its over fueling and running rich.

Also, on the back of the engine (right next to where the hood lamp is, also next to the distributor), there is a flat 4 wire connector with nothing connected any ideas of what this would be to? Would this connect to the auto tranny if it had one? Didn't have a chance to really look to see if something was disconnected.

Any other suggestions on what to check or what it could be? I have a cable to read the ecm and codes. I also have a tbi fuel pressure guage, but will need to get the adapter to plug the fuel line into. I'll get the cat replaced and get the exhaust sealed up and see where I'm at. What could have caused a cat to get clogged besides 270,000 miles

Maybe all is fine, just old cat clogged up the exhaust and now the cut open exhaust is causing it to run way rich. Guess we'll find out.

[jb1016]

Looks like a nice truck, hope you get it figured out.

[Boog]

Good looking truck inside and out for the miles.
I'd start with the basics.
scan for codes
check fuel pressure anyway
check ALL ground wires and battery cables

running over rich can damage a cat
burning coolant can damage a cat, as in leaking intake gaskets
and cats do wear out. 270,000 miles on an original is a lot

[Ackattack]

Originally Posted by Boog

Good looking truck inside and out for the miles.
I'd start with the basics.
scan for codes
check fuel pressure anyway
check ALL ground wires and battery cables

running over rich can damage a cat
burning coolant can damage a cat, as in leaking intake gaskets
and cats do wear out. 270,000 miles on an original is a lot

Yeah compared to my 97 the interior is WAY WAY nicer with 50k more miles and 2 years older. This does have a little rust in the cab corners that my 97 does not, but otherwise the exterior is nicer too.
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[Ackattack]

I pulled this truck into the garage tonight to start working on it.

First thing I set out to do was address the cat. My thought was just to cut the back of it off, clean it out, then reweld. Much to my delight, there was a flange on the back of it and I unbolted it (2 bolts is much easier than welding )

So the cat definatly has some clunking around going on. This is what fell out of it:


So with it cleaned out I went to re-install it. Cleaned up the edges with a wire wheel on the grinder and started welding it back in. Because of the orientation, seeing from about 10 o'clock to twelve o'clock was not possible. What to do? I broke out my Iphone and used the front camera so I could see where the mig wire was, put the phone down and made a tack weld and then moved on to the next one. Isn't technology great!

So then I fire the truck up. Obviously its much quieter, but still not running like it should (not real surprising) So I pop off the air cleaner and start looking at things. The first thing I wanted to check was to see if the timing connection was plugged in (I forget the acronym for it) So as I'm looking for that, I find another problem:



This spark plug wire was not in the holder, and sitting on the back corner of the exhaust manifold. I went ahead an unplugged it. I fired the truck up and it seemed to run idle a little better, but obviously (again) not great. I looked around the garage to see if I happen to have an old spark plug wire, but I didn't. So tomorrow I'll get a new set and throw them on. Hopefully after that it will run nice and smooth.

BTW I did locate the timing connector, and it was plugged in as it should be.

One other thing I noted was the very front passenger side exhaust manifold bolt is broken off in the head

[Palf70Step]

That would have been interesting to have pictures of you welding with the iPhone

Hope it goes smooth getting this one running rgith again.

[Boog]

Hey now a burned plug wire will definately hurt the idle quality and fuel consumption. I bought an 88 GMC shorty that idled terrible but the truck was solid. Once going it seemed to smooth out pretty good. Long story short, I bought it right and went straight home and did a tuneup on it with new wires, cap and rotor. Smoothed it right up. One of the boots had a split in it and was arcing over to the exhaust manifold.
Man that cat was full of crap! I wonder how much of it was blown downstream into the muffler.

[Ackattack]

Got the spark plug wires changed out and took a drive around the neighborhood. Still having some issues. So I hooked the ol' laptop up and I've got a couple of codes:

14 CT high (could be cause I let it idle while I was messing with computer and it got hot)
22 TPS low (the signal is jumping all over the place, from -1.4 to 55)
33 MAP high
43 Knock ESC
54 Fuel Pump Relay Failure

Any suggestions on where to start?

[Ackattack]

What's this connector to? ESC maybe?


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[Warrens69GMC]

Check your wire going into the map, and check to see if it has a 5/32 regular hose going to it - it The plastic hard line leading to the map usually gets replaced with regular hose or is broken and it will cause the truck to run like crap.

The ESC is usually right next to the power brake booster and is 5-pin.

[Ackattack]

Connector has a black, black/white, and brown wire.

Looking at the wiring diagram for the engine, I didn't see a sensor with those three wires. I did note that all of those wire colors are used as grounds at some point.
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[Ackattack]

So I changed out the TPS and now that reading is nice and steady. The truck will idle nice and smooth with no a/c

if you turn on the a/c, it stumbles and doesn't idle real well and died a few times.

Then I tried moving it in the driveway and when you put it in gear and let off the clutch it pretty much sputters then dies. Even if I revved it up and tried slipping the clutch it dies.

I cleared all of the codes and now I'm just getting the code 33 (MAP high). So I'm going to see if there is a way to test the map sensor and might have to replace that one as well.

[Ackattack]

Oh and I checked the little hoses going to the map sensor, and egr valve. They were fine
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[Boog]

Progress. You're getting there.

[Ackattack]

So I checked the MAP sensor and it is good acording to the manual (I also got a new one, plugged it in and no difference)

Still getting a code 33.

While I was messing with it, trying to get it to run/keep it running, I had my foot on the gas a little, and I saw a flash of something (I assume fire back out the throttle body...I was in the drivers seat and the hood was up)

Then as I'm still messing it sputtered and it sounded/appeared like something kind of exploded (kind of a small puff like a pressure relief or something). Some liquid also shot onto the windshield.

After both of the incidents, I could not see any damaged items in the engine compartment.

One thing I would like to do is check the timing, but I can't keep the darn thing running long enough to check it.

[54 jimmy]

spray some carb cleaner at the base of the tbi while at idle. make sure the engine is not hot when you do this. if it dies then you have a bad tbi gasket. this will affect the map as you push the gas it will draw extra air in and cause it to stumble/die. had this problem with one of my s10's before. also check the pcv hose port on the tbi if it is plugged it will cause pack pressure in the motor and run like crap. clean out with some carb cleaner or I like the air plenum cleaner it breaks up the carbon better. hope this helps.

[Ackattack]

After doing some reading last night, I read about one guy having similar problems and he unplugged the cts and it improved. So I started looking at the CTS. I unplugged it and got it running. It would idle nice and smooth. The temp got up to normal temp (~185) and I checked the resistance on the CTS and it was right where it should be (260 ohm IIRC). Also, the power wire going to the sensor had the required 5V.

While it was running nice and smooth, I checked the timing real quick. With the timing wire disconnected, it was at 0.

I started the truck a few times, and it started up pretty much normal (tbi engines don't seem to fire immediately like LS engines due).

Then I reconnected the CTS and it was hard to start again, and once it was started, it was stumbling.

[Ackattack]

So the cts is good. I tracked it on the computer and it follows along right with the gauge on the dash.

So apparently the engine runs rich when it's cold, and with the cts unplugged the ECM thinks its cold, therefore it richens up the mix.

So I'm thinking I have low fuel pressure. I don't have the fitting for my fuel pressure gage, so I'll get one of those. In the mean time I'm going to change the fuel filter, just as a matter of maintenance. I might get lucky and that fixes it. We shall see.
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[54 jimmy]

hope you track it down. seems like your getting there. good luck.

[Ackattack]

Got the fuel filter installed, it was idleing good (still hard to start) so I was going to take it for a spin around the 'hood. Idled out into the street, then went to go, and there was no power, stalled out, so I figure there's no reason to mess with trying to limp around the block, so I just pulled it back towards the garage.

Ordered a fuel pressure tap for my guage. I'm guessing its the pickup hose going to the fuel pump that is known to fail. The PO told me they had put a new fuel pump in it, but it could still be that.

[54 jimmy]

maybe you have a bad fuel pressure regulator in the tbi.

[jb1016]

Originally Posted by Ackattack

The truck will idle nice and smooth with no a/c

if you turn on the a/c, it stumbles and doesn't idle real well and died a few times.

Sounds like, once you get your fuel pressure right, you might need to check your Idle Air Control valve as well.

[Ackattack]

Originally Posted by 54 jimmy

maybe you have a bad fuel pressure regulator in the tbi.

could be. I'm going to check the hose between the sending unit and fuel pump first, as this seems to be more common. But won't really know until I have the fuel pressure guage.

Originally Posted by jb1016

Sounds like, once you get your fuel pressure right, you might need to check your Idle Air Control valve as well.

I took it out and cleaned it the other day, it was pretty clean and didn't have any effect. But again, with the CTS unplugged it idles fine.

Hope to get it figured out this weekend.

[Ackattack]

Got my fuel pressure guage adapter and got it installed. Fuel pressure was 6psi. I was told by the PO (owned it for just a short time) that the owner before him had changed the fuel pump. Well I think there was some mis-truth somewhere along the line. The fuel pump I pulled out didn't look new.

So I put a new fuel pump in, got it all buttoned up and checked the fuel pressure at 12psi!!!!

So I drove it around the neighborhood, it still has some "issues"

First, when you try to start it up, it takes a while longer/multiple attempts to start it. Once started it idles fine. When you get to going it doesn't have much power. As I was driving around I kinda got into it a little to see what it had. It slowly started accelerating (2nd gear) until about 3500-4000 rpm range, then something "switched" and it had a brief moment of power and "threw you back in the seat". As I continued to drive you could kind of feel a few surges in power, but for the most part it felt really doggish, like the timing wasn't advancing at all.

So here's what we know:
Good fuel pressure (new pump and filter)
Verified that the CTS is good
Verified the MAP sensor is good
Verified vacuum lines are good
New TPS sensor
New spark plug wires
Timing set to 0
IAC removed/cleaned/reinstalled.

So what should I be checking for next?

[Warrens69GMC]

Check vacuum for reliable operation (~18lbs steady)

Ign control module test.