TXBowTie40

iTrader: (2)

Been slowly (and I stress SLOWLY) getting my 1990 GMC K1500 extended cab up and running with the Vortec 350 TBI in it.
When I took it out for the first test drive, I got a Code 44 Lean O2. Tested fuel pressure, got 14psi at idle, checked for vacuum leaks, etc. The problem persisted. Got a throttle body from a cop car from a friend here in town, put it on after cleaning it up good, the problem was still there.
Took the truck to a local shop to have it hooked up to a scan tool....he told me the TPS was bad, as the voltage was too high at idle and only maxed out at 3.6v at WOT. So, 160 bucks later, I take the truck home, along with a suggestion that I replace the plug wires, as well as consider getting a new throttle body as the shaft is loose and causing air leaks which is making the ECM do crazy stuff.
I replace the plug wires, check everything over again, and take it out on the road for a test drive. About 55mph, the SES light comes on again, the engine just goes flat, and, when I get back home, the same Code 44 is set.
Since I do enjoy goofing off in salvage yards, I decide to visit the one near me. There, I find a 1995 GMC K2500 about to be parted out. The throttle body is there, along with the complete wiring harness and PCM.
Remembering Fast355's write up, I ask about the price for the TB an PCM, and I can get both for $150. They will throw the wiring harness in, provided I am willing to pull it myself.
The throttle shaft on this throttle body has no slack in it, and everything is very clean in appearance.
I am thinking about getting that throttle body, splicing the newer style TPS connector into my 1990's harness, and seeing if the lean condition goes away. Swapping the 1995 PCM and harness will have to come at a later date, cause right now I don't have a laptop or any of the cables and such to program anything at this time.
Am I on the right track, or am I going about this all wrong? I looked into having Affordable Fuel Injection rebuild my throttle body, but their price of $250 and up (if more than a basic rebuild is needed), plus they didn't answer my phone calls or emails, makes me leery of them.
Oh yeah........if you guys know anyone wanting to part ways with a laptop suitable for tuning our vehicles, have them PM me.......lol! Used laptops are next to impossible to find here in the area where I live, and I can't justify spending 700+ on something that will be in my truck 90% of the time, as the only thing I want one for is to use as a tool for programming.
Thanks in advance..........

RFmaster

TXBowTie

Sounds like you are having fun with your 1500 plus its a long post to boot. Regarding Code 44 and leaky TB shaft. Did you check your Fuel Pressure while running engine at higher RPMS?? It is possible that your fuel pump is going flat as engine needs more fuel at higher loads. I know, you measured 14 psi at idle, but what is at higher RPMS? Check it. Another cause for Code 44 could be an exhaust leak - dumping additional air into exhaust stream (do you have AIR injection system?).
Leaky TB shafts can be repaired by any competent carburetor rebuild shop. Typically they will sleeve the shaft and will be good as new at much lower price then slapping a newer TB.
New TB and PCM can be adapted, but at a point of being over cautious I would rather figure out Code 44 first before doing a brain transplant. Drafting a newer style TPS connector to existing harness is straight forward - get pigtail from JY in addition to harness (I do not like to cut harnesses).

Regarding a lappy - my automotive lappy started as two broken 300MHz Pentium 2 lappys used (or more approprietly abused) by my company sales people. When IT was cleaning junk storage (dumping e-waist) I grabbed them. Long story short - older lappys make better data acquisition comps since they have true RS-232 port in addition to USB. Older machines (circa Y2K) run OK with Win2K if you install enough memory. They are slow - just deal with it! Newer lappys do not have RS-232 and you have to resort to PCMCIA cards or USB to RS-232 converter cards. Even worst, newer (cheap) lappys do not have PCMCIA slots - beware.

//RF

TXBowTie40

iTrader: (2)

I appreciate the feedback RF.
Yes, I checked for exhaust leaks, found none. There are no, none, nada, ZERO carburetor shops in this area, so having the throttle shafts repaired was not an option.
Fuel pressure held steady during the test drives I did, which did include some WOT runs......lowest it dropped was to 11psi, still within parameters.
Finding a used laptop is my problem. I build my own desktop systems and am not afraid to go into a laptop either, just haven't had any luck whatsoever finding one suitable for my purposes. I could buy a new one, but like you said, what I really need is an older one with the proper connectors and ports.
Thanks for your response!

TXBowTie40

iTrader: (2)

Picked up the PCM and throttle body yesterday, am gonna go harvest the red and blue PCM connectors on Monday........
Bought a throttle body rebuild kit from the local O'Reilly's, along with some 3M Throttle Body Cleaner and went to work.
Everything went surprisingly smooth......I can't say enough about that 3M stuff.....it cleans as well or better than anything else I've ever used, plus it lubricates at the same time.
Grafted the new style TPS connector pigtail into my existing harness, and she started right up. Idle is smoother, no lag in throttle response, and now I can get full throttle with no codes at all.
Next on the agenda is the PCM swap, and for that I'll be picking dimented24x7 and Fast355's brains..........