gbettner

iTrader: (2)

Hi all, started a thread about o2 sensors in the general engine section and it kind of died. Figured posting in the TPI section may help me out.

I've installed a 350 TPI out of an 85 corvette into my 89 Iroc formerly with a 305 TBI. I converted my harness to speed density TPI, runs like a scalded dog.

Only problem is if I nail the throttle and run it out it pulls great and performs great until I let off the gas. I start smelling strong gas smell and my eyes even start burning it's so strong. I can look in the rear view mirror and see a long white vapor trail of smoke/vapor , if I pop it in neutral and give it a revduring this it will revv out some more white vapor/smoke out the tailpipes.

It doesn't smoke at start up or during revving or hard acceleration. Only after a hard run and decelerating from a high speed. ( Say I wound it up to 120mph and let off the gas just decelerating/coasting......after 5-10 seconds I can smell and see thegas/vapor/smoke and my eyes start burning it's so strong)


A few important details are.....

I have headers

I had stock 1 wire o2 and code 13
Installed afs-75 ( Bosch equivilant) heated o2 sensor and wired in 3 different ways before I got it right. (still get code 13).

Doesn't seem to act up right away, only after you drive it long enough to get into closed loop?

I don't know where to go from here. After I finally got the heated o2 sensor wiring somewhat figured out and got heat to the o2 sensor that only left 2 wires. One was a ground and the other was the sensor wire. I was a little confused about which one went where so I test drove with the final 2 wires hooked up like I thought they should go and still same problem on deceleration and set a code 13. So I was aggrevated and flip flopped the ground and sensor wire and test drove again. Same exact problem and still set code 13.

Now I'm thinking either
-I burned up something in the ECM since I may have hooked up ECM o2 sensor wire to ground and/or 12v at some point.

- used o2 sensor I got from junkyard isn't compatable

-or a deeper problem I haven't exposed yet.


If anybody can understand and make sense of all this jibberish I just attempted to explain and give me some ideas I would be very grateful.

Thanks

vetteoz

iTrader: (13)

Most obvious thing would be to follow the DTC 13 diagnostics and see what the actual problem is ; instead of guessing

http://www.chevythunder.com/o2_sensor_diagnostics.htm

gbettner

iTrader: (2)

Thanks, I'll get with my son and see if he can help me get set up with software and cable. It's a little beyond me right now but I'm sure he'll help me understand. I'll see what kind of cables the parts store has and start looking for some software.

gbettner

iTrader: (2)

Well I scored a snap on MT2500 scanner so I could read data and get to the bottom of things and I now have a deeper problem. It won't read anything out of the port. I'm afraid something may be off after repinning TBI harness to speed density. ( Scanner says "unable to connect" or something.

Tuned Performance

iTrader: (92)

Did you change the aldl pin from E to M ?

Tuned Performance

iTrader: (92)

Btw you need to send me the mt2500 to make sure its working ok lmao

gbettner

iTrader: (2)

Nope, sounds like I'll be doing it right now. I'll let you know what happens. Thanks!

gbettner

iTrader: (2)

Well believe it or not I screwed that up, I swapped pin E and M but scanner still read "unable to connect". So I swapped them again thinking maybe I got them mixed up and plugged them right back where I took them from and scanner still read "unable to connect". So I unplugged E and left hanging to see what happened and still same results. Now, in all the confusion I lost track of which wire should be M and which should be E. They're both the same color orange. O the humanity!

Was it supposed to be a swap of E and M or put E in the M spot and leave the old M disconnected?

Tuned Performance

iTrader: (92)

E and M are tied together the only thing that matters is that you have that serial data line to M. Key on engine off it should be 2.5V or higher.

gbettner

iTrader: (2)

I have right at 5 volts at terminal E and at terminal M. So are you saying to splice the 2 together and insert into M?

I'm confused on why originally E was to be switched to M if it's the same wire.

Tuned Performance

iTrader: (92)

Sorry, not all obd1 vehicles had 2 wires . When they did they split and one went to e the 160 baud and one side of the split went to M the 8192 baud.

gbettner

iTrader: (2)

After switching ECM's now the darn thing is communicating with the scanner....



I'm not sure what I'm looking at but it says....

Open loop

O2 (mv) 394 Integratr-128

O2 ready no

O2 crosscounts - 0

Exaust oxygen - lean



Never went into closed loop, just keeps setting CEL after it runs for a few minutes.




Does that tell anybody something?

Tuned Performance

iTrader: (92)

Just guessing the engine is cold ! Let it warm up and see if your o2 starts swinging.

gbettner

iTrader: (2)

Let it run for over 10 minutes at 1200 rpm, still same results. Swapped the ground/signal wires with each other to see if that did anything and no change. Reads the same if it's hooked up one way or the other, even if I leave them both unhooked.

Tuned Performance

iTrader: (92)

I wonder if there is a issue with the ecm ground for the o2 pin e15. I can't remember your post awhile back if you hooked up a volt ohm meter on the signal wire in mv mode and see any movement to rule out the o2 sensor.

8T9Formula

iTrader: (1)

Hi there!

Are you still getting Code 13? If yes, follow the link to the diagnosic chart or get a copy of an appropriate service manual and find and follow the troubleshooting for Code 13 there.

Basically, Code 13 sets when:
Engine has achieved operating temp
Engine has been running for at least 2 minutes
Throttle position is above 5%
O2 sensor signal voltage is fairly steady (between .35 & .55 volts)
All above conditions true for at least 60 seconds

If Code 13 is present, the system will remain in Closed Loop and run fairly rich all the time...

gbettner

iTrader: (2)

I've tried about 3 or 4 different o2's with same results. If it's ok just to splice in a good dedicated ground to pin e15 I'll do that this evening and see if I can get a mv reading from an o2 wire with a multimeter. I hooked a multimeter up at one point earlier in this adventure ( a month or so ago) and got a lot readings all over the place like I should have. Just need to home in on what's going on.

It is ok to splice in a ground to e15 isn't it?

Tuned Performance

iTrader: (92)

Sure is all the grounds get hooked to the engine block, adding a ground strap and extra ground to e15 can hurt unless you get emi so keep any new grounds aways from ingintion wires and the raidio.

gbettner

iTrader: (2)

Spliced e15 to ground and still same results. I can get some bouncing around erratic readings with the multimeter on one of the o2 wires, I'm gonna call that the signal wire and run it straight to e14 on the ecm tomorrow and see what happens. This is kickin my but!

gbettner

iTrader: (2)

Alright, mostly good news.......

I temporarily ran a wire directly from the o2 signal wire across the windshield to terminal e14 of the ECM. IT WORKED!!!! ( for the most part).

It know reads o2 signal and goes into closed loop.I'm still getting a code 13 if I hold it at abot 1500 rpm's for a couple minutes. When that happens the o2 millivolts lock at 394...... INTEGRATR reading freezes at 128.

Before that happens it runs in closed loop and feels great while revving. o2(mv) stay at 4 and the INTEGRATR reading is 180 at idle and if you rev it up hard it will drop to 128 then quickly display a quick series of readings building back to 180 when it drops back down to idle.

I think I have it hooked up right now since I'm getting closed loop for a little bit. Now I just have to figure out why I'm STILL getting a CEL.

Does any of this give anyone an idea of what I should do next? Maybe o2 sensor bad or not compatable? It is a used one from junkyard (AFS-75 I think). I have some others I can try I guess. If anyone knows something that could help please let me know.

Thanks

8T9Formula

iTrader: (1)

Code 13 sets because the O2 sensor signal voltage stays between .35 & .55 volts. It should switch between .1V and .9V several times per second while in closed loop.

You mentioned you have headers - an exhaust leak can draw in O2 that can "fool" the O2 sensor into thinking the AF mixture is sightly lean (below .5V).

For what it's worth, the Integrator you are looking at is the GM OBD1 term for Short Term Fuel Trim - when it goes high (above 128) the system is adding fuel because it believes the AF ratio is too lean. When in closed loop, the ECU is trying to keep the Integrator at 128 all the time. Consistent and significant changes in the Integrator, rich or lean, will cause the Block Learn (the GM OBD1 term for Long Term Fuel Trim) to shift up or down. This is the area of the computer that "learns" the fuel trim and adjusts for it as it is operated for weeks, months, etc. It is also reset to the midline value of 128 if the computer memory is lost with a battery disconnect.

Hope that helps!

gbettner

iTrader: (2)

Thanks for the response. Good info.

I don't think I have an exaust leak though, I don't hear or see any leaks anyways. I'll try to look real good again tonight for signs of leaks, maybe even just past o2 bung at collector but it sounds ok.

RBob

iTrader: (1)

This is the part that I would be looking into: "long white vapor trail of smoke/vapor".

Sounds like under high vacuum conditions coolant is being pulled into a chamber or two. Coolant will ruin an O2 sensor.

RBob.

gbettner

iTrader: (2)

Very interesting. I have an oil pan gasket /rear main seal I'm going to have to yank the motor back out for anyways eventually. I might as well do a thorough compression check prior to ( to confirm bottom end is sound) and then slap some head gaskets and lower intake gaskets on it while I'm at it. I'll get my temp wiring reworked permanently for the o2 and try a different one that hasn't been installed yet to see how it acts out of curiosity then post results. If I remedy the o2 and still have problems I'll be yanking that sucker back out. Thanks for the response!

Tuned Performance

iTrader: (92)

I kept scratching my head, and the thought was silicone poisoned but how can that happen over and over. The man with all the answers

gbettner

iTrader: (2)

Just an update, I had way too many jobs lined up to pull my Iroc motor back out but I'm getting there. Finishing up a blazer engine swap and got one more full size chevy engine swap this weekend then I can finally get my baby back in the garage to pull motor back out and change oil pan gasket and intake gaskets.

gbettner

iTrader: (2)

Pulling my engine this weekend. Did a compression check on all cylinders before unhooking everything. I have 160-165psi on all cylinders. All 8 sparkplugs were just about fouled out (rich/black). Looks like severe over fueling but with compression that good I thing the cylinders and rings are sound..... not oil consumption.

gbettner

iTrader: (2)

Got motor out and pulled intake off. Looked VERY VERY closely at all intake and coolant passages on the intake gaskets. Couldn't find any imperfections,cracks,leaks, or signs of leaks. Beginning to wander if the haze out the back is just severe over fueling since I only have about 20 miles on a brand new set of sparkplugs that are already solid black and making it very hard for engine to start lately.

No big deal if it wasn't the intake gaskets though, I had to pull motor back out to change out corvette oil pan and leaky gasket (only to find out I'll have the delete widage tray, switch out main cap bolts involved with windage tray, and switch oil pickup to work with the right oil pan). Guess I'll go ahead and install a new oil pump just for the heck of it.

I'm putting new head gaskets on also just to be safe.

Very suprised with internals of this 85 vette motor, it's perfectly clean with NO oil sludge or residue whatsoever. Must be very low mileage!

gbettner

iTrader: (2)

Well, problem exposed. The engine was stored dormant too long. Pulled the heads off and found signs of rust in the cylinders at some point, cylinder #5 had some bad scratches in it and several others showed evidence of rust. carbon was cleaned off of the bottoms of several pistons in areas pointing towards blow-by. Crazy that this thing had such great compression but final diagnosis is rust damage in cylinders and maybe some cracked rings from long term storage (at least 10 years from what I was told).

Such a shame a pristine low mileage 5.7 TPI motor is junk. I would just bore it but I've decided instead of investing a bunch of money in rebuild I'll just cut my losses get a good used vortec longblock with Scoggin Dickey intake and pick up some noticeable horsepower while I'm at it.
( Thanks for the idea TP)

I'm trying to give myself a crash course on this swap. I'm getting exited.


If anybody in Indiana wants a very clean complete corvette longblock that needs a simple bore job let me know.

gbettner

iTrader: (2)

Picked up a VERY nice 97 Vortec 350 at the local pic-a-part today. Very clean with minimal wear. No lip on cylinder walls. Getting exited again after the depression from the other motor.

Tuned Performance

iTrader: (92)

Nice find

gbettner

iTrader: (2)

Well, too good to be true, piston to cylinder wall clearance was up to .004 on a couple cylinders so looks like I have to get the block bored to be safe. O well, if your gonna do it do it right I guess.

vetteoz

iTrader: (13)

383 time?