Hi all,

Got a bit of a problem, and was wondering if y’all could help.

Working on my 1993 Pickup (22RE) 172K miles. When I bought it, the gas mileage was running around 21/gal. The head gasket blew about a year ago. I rebuilt the head and changed out the plugs, wires and fuel filter while I was in there. The only problems were finding oil in the plenum, and an old helicoil on the exhaust side let go as I was installing the manifold, resulting in a small exhaust leak.

After the rebuild, it ran like crap and the gas mileage went down to about 15/gal. That’s when I found out that TDC is actually one tooth off. During the process of figuring that out, I hollowed out the cat, thinking that might help. Fixing the timing didn’t help the problem. I put a new cat on about a week ago. The increased pressure blew out the manifold gasket completely within a day. Gas mileage is now running around 12/gal. Also, it now skips and misses occasionally, worse when I hit the gas.

It’s not losing power. No obvious vacuum leaks. The valves are adjusted properly. Not leaking fuel. O2 sensor is good. Seafoam didn’t help. However, there are two broken sensors by the oil filter. One looks like a wire was ripped out of a connector, the other looks like the sensor was ripped out of the block. I think one is the knock sensor. These were broken when I bought the truck.

I swore that if I ever had to pull the head off again, the engine’s coming out. At this point, I’m considering a complete rebuild of the engine.

Going through the forum, I see a lot of suggestions related to the injectors and emission system, but I have no idea where to start. I would hate to rebuild, only to put potentially bad parts back on. Does anyone have any suggestions before I spend a crap load of money?

Thanks!
Doc

 

www.ncttora.com/fsm

:wabbit2:

 

welcome to yotatech.

first off, id get a new manifold gasket and put a new stud in there where the heli coil was/is. If not new studs all together. A manifold leak will kill mpgs IMO.

Can u show any pics of the missing/broken sensors>?? It would help a lot.

IIRC, the oil pressure sender gauge sensor is by the oil fliter. Usually protected by a plastic cap. ANd a coolant temp sender or sensor is also by the the oil filter. Again, pics would help.

I didnt think the engine could run without a knock sensor?? Or it would run really bad?? This is where someone else can chime in.......lol

Good luck, youve come to the right place!

 

Well the timing being off would effect the mileage.

When you say you rebuilt the head just what did you do???

If the mileage fell off that much after the head rebuilding I would think about that.

had you in fact been getting 21mpg??

Did your driving habits change?? to lower the mpg.

Colder weather winter blend gas more idle time all can lower mileage.

No knock sensor keeps timing at the base level in kinda limp mode but I don`t remember for sure.

 

Hi again,

Thanks for the suggestions!

I had the last 4 days off work, so I spent it in the driveway.

Found that the exhaust leak was not actually the manifold gasket itself. The stud with the bad helicoil had fallen out completely, resulting in an empty hole. I sunk a couple grand into my wife's VW last week, so pulling the head and fixing the threads again is not an option. I channeled my inner MacGyver and packed some aluminum foil into the hole. Problem not fixed, but temporarily patched until fundage improves. Gas mileage improved to 15.5/gal and running a lot quieter.

Once the leak was fixed, I erased the trouble codes and drove it for a while to see what would pop up. The new codes indicated a bad knock sensor, and a coolant temp sensor. I figured out that one of the busted sensors on the block (the one that was ripped out) was the knock, and the other was the oil pressure sensor (the broken connector). I absolutely SUCK at soldering, so I took the connector to an auto electrician in the area. He soldered on a pigtail and sealed it with permatex. Only charged me $10.

When I got home, I changed out the knock. Luckily, the wiring was intact, just had half of the sensor hanging off of it. I wired in the new pigtail for the oil pressure sensor, and changed out the coolant sensor.

For the first time in years, the check engine light is off, and staying off. The truck runs like a raped ape, even better that the day I bought it (ebay). There is no hesitation, no surging, no misses. Just runs smooth as hell. We'll see what happens with the gas mileage.

I just have a random, extra connector near the fuel line, up by the intake that I can't find a home for. I cant remember if it was like that before the head was rebuilt. I'll ask that question in another thread.

Yall, thanks for a hell of a site. The only way I was able to figure this out was by searching through this site, and through google images, which linked back to yotatech. Hopefully, as I learn more, I can give advice as well as benefit from it.

 

is it this one in the pic? this goes to nothing on most of our trucks. I believe I remember it explained as something with California emissions motors (could be terribly wrong too, but it goes to nothing)