96 riv no start, injectors not pulsing. fixed w/wire harness +new issue

Mr.Riviera wrote:

I've been trying to track down the short with a multimeter. Replaced the maf hot line (pink 439) from the maf plug to the harness. Still low v at sensor with harness plugged in. Harness unplugged shows continuity and 9v at the same pin. Car running the fuse shows same .01 v as the sensor. Fuse internally had melted and refused(no pun intended).
Looks like I'm onto something just need to find the draw/short.

I agree.

Times I've had an electrical gremlin in my Riv have been times I worked on the electrics, even the cigarette lighter connections, without disconnecting the battery. Nowadays when I go in for any electrical work other than maybe a bulb change, I pull the battery cables. I dislike doing that because I don't want to scratch the rear seat leather. However, I dislike the gremlins even more. For work just under the hood often disconnecting the battery at the under-hood power point would be enough. However, it's also a good time to inspect and clean the terminals and main ground, so I just pull the thing.

Hi Matthew. I agree this doesn't seem like a VATS issue. To rule it out, have you swapped in a 2nd PCM module? Running with MAF disconnected can cause rough idling, even stalling. Have you ruled out the MAF sensor as the problem? You mentioned disconnecting IAC valve made a difference. Have you considered replacing this part?

I have replaced the Ckp, PCM, BCM and did a VATS bypass so far. None have fixed my problem.
I have unplugged both the IAC and the MAF and the car will run on the bonneville OSID (runs on VE tune). With both sensors unplugged the riv OSID the car will just crank and never fire up. Stalls sometimes with the IAC unplugged, but run the same MAF or no MAF with that tune.

I think the MAF fuse i replaced last night blew immediately when key was turned to on. So i most definitely have a short somewhere post IP fuse box, and its the pink MAF power wire because that was completely replaced from the sensor to the harness as close as i could cut it and crimp in a connector.

Im betting whatever it is shorting out to is what is causing the no-start with the riv OSID and the start with the bonneville OSID because the bonneville pcm wire setup is slightly different. For example maybe its looking for MAF g/s on wire 17 and the riv maf is wire 54. But the riv wire 17 is coolant temp so it sees a number for Maf and is ok to start.

Just throwing this out there... I've been watching this thread so far but haven't had anything to offer.

This is purely anecdotal, since I just went through something sort of the same and I know people like to see their own solution in other kind of similar problems, but it might be something to rule out. I feel like albertj was on the right track at the ignition switch. There is a whole bunch of stuff that actually runs through there for the car to run and stay running besides jumping to VATs. At the end of the lock tumbler at the left of the steering wheel is a rotating switch barrel with quite a number of engine-running critical wires that get switched on when the key is turned on. The key rotates through the steering column and in turn rotates this barrel switching mechanism. In my case, the screws holding that switching thing onto the steering column were getting loose, causing *some* of the many connections that go through it to intermittently loose connection. This caused a host of really random symptoms/starting problems/running problems/etc.. It was random but I only got pointed at it when I found the car would run with the steering wheel tilted all the way up but would die if I tiled it down. I'm not saying your issue is exactly the same, but it might be something to investigate as something might be crossing/shorting or just not quite making connection in there. Perhaps the bonnie tune doesn't do some of the checks through the ignition switch tumbler as the riv does?


Also will the 96 not start without the maf connected? My 98 could, but I haven't tried on my 96. The 95 for sure won't due to a lack of a MAP.

Thank Karma. Yes my car always would start with no MAF, even with the LQ4 MAF i currently have.

If i am unable to find the break in the maf wire i will pull the column apart and inspect the lock mechanism. I could only see 1 wire (really 2 white wires) coming out of there and that read the resistance of the key. When measured with key on it read the same as the key.

Karma wrote:

Just throwing this out there... I've been watching this thread so far but haven't had anything to offer.

This is purely anecdotal, since I just went through something sort of the same and I know people like to see their own solution in other kind of similar problems, but it might be something to rule out.  I feel like albertj was on the right track at the ignition switch.  There is a whole bunch of stuff that actually runs through there for the car to run and stay running besides jumping to VATs.  At the end of the lock tumbler at the left of the steering wheel is a rotating switch barrel with quite a number of engine-running critical wires that get switched on when the key is turned on.  The key rotates through the steering column and in turn rotates this barrel switching mechanism.  In my case, the screws holding that switching thing onto the steering column were getting loose, causing *some* of the many connections that go through it to intermittently loose connection.  This caused a host of really random symptoms/starting problems/running problems/etc.. It was random but I only got pointed at it when I found the car would run with the steering wheel tilted all the way up but would die if I tiled it down.  I'm not saying your issue is exactly the same, but it might be something to investigate as something might be crossing/shorting or just not quite making connection in there. Perhaps the bonnie tune doesn't do some of the checks through the ignition switch tumbler as the riv does?  


Also will the 96 not start without the maf connected? My 98 could, but I haven't tried on my 96. The 95 for sure won't due to a lack of a MAP.

Actually I have to thank one of the techs at an undisclosed GM dealer who mentioned to me that Riv used a very similar ignition switch to those subject to recall but in his personal opinion wasn't listed in the recall because too few Rivs were made. The cars in that particular recall are not the only ones with gremlin-infested ig switches; the Riv supposedly uses an ig switch similar to that in the S10 (I think same switch different pinout in the rectangular connector), and they are not problem-free.  My problem at the time was a sort of random stall/no restart. We put noids in parallel with the injectors and added jumpers so i could see them under the back edge of the hood.  When the car stalled i recorded the state of the noids. That was how we found it the first time.  A couple of the gearheads (gearhead is a term of endearment, folks) at the dealership had come up with how to connect the NOID lights so as to disclose the problem.  Not all the NOIDs were attached to the injectors.  Anyway - when I reported the pattern (by cellphone while waiting for a tow) they knew right away it was the ig switch.

The second time, I had put about  another ~100,000 miles on the car and it started acting up.  I'd have to check my log as to what was wrong, but I do recall I replaced the switch again to fix that.  I think it was a no-reason VATS no-start or some such silliness.

This time (just a few months ago) after yet another 100,000 miles I noticed my ig switch was doing weird things, for instance, if I pressed on it with no key in the warning chime would fire... and I could not turn the key to the Accessory position any more.  It was also putting the car into the VATS no-start, at first intermittently but as time went on, more often.  My elderly dad insisted it was the starter that was busted, I humored him and replaced it (its not terribly difficult nor expensive on the Riv) and that did not fix anything.  I was planning a steering wheel swap anyway (mine was chewed and I got a nice deal on a NOS unit) so I had the ig switch and keyway (and turn signal switch) replaced as part of that maintenance.  WHAM, the VATS no-start and the chime problem vanished, and of course I could turn to ACC again.

It was those experiences and the knowledge that a number of systems rely on the ig switch working that I suggested you check  it.

Mr.Riviera wrote:

Thank Karma. Yes my car always would start with no MAF, even with the LQ4 MAF i currently have.

If i am unable to find the break in the maf wire i will pull the column apart and inspect the lock mechanism. I could only see 1 wire (really 2 white wires) coming out of there and that read the resistance of the key. When measured with key on it read the same as the key.

Those two little wires are for the key part. The whole lock tumbler goes through the steering wheel and this(bottom left of pic) gets turned with the key:
http://www.rockauto.com/info/301/D1482D_Primary.jpg

It attaches to the left of the column and the other end down at the floor.

18 wires in there.

Is there a way to test that or am i dropping $130 on a hope that it fixes it.
I know for sure that i have no V at my MAF sensor and no V at the fuse (fuse is good) with the connector plugged in, so i either have 2 separate issues that came up at the same time, or that device controls power to the MAF and injectors with key on.

I think you could unplug it at the floor and use a multi-meter to test continuity on all the pins with the key turned... They should each have contact in at least one of the 3 active key positions(on, start, and accessory) depending on what they are. You could also check from the + line at the MAF to the firewall/floor connection just to see if it goes there. I can see later this weekend if my FSM from the 96 lists what the wires are if you want?

I have a FSM and its the pink 439 (C2) wire on the connector. When i checked the other day it had ~9V to it. Not sure if its supposed to have 12+ or not but FSM says maf connector should be 5-7V on the troubleshooting part for the P0102 code

Mr.Riviera wrote:

I have a FSM and its the pink 439 (C2) wire on the connector. When i checked the other day it had ~9V to it. Not sure if its supposed to have 12+ or not but FSM says maf connector should be 5-7V on the troubleshooting part for the P0102 code

A few posts ago you mentioned a short that was blowing a fuse.

Before you replace the ig switch, suggest you fix that short asap.  However, they could be related and the ig switches do wear out.  Have to see a wiring diagram on that one. Would not be alarmed if coincidentally both problems obtained.

Tore into the harness again this weekend. 12V+ at the fuse for MAf, nothing at the firewall pin C2.
So i ran a direct wire to the 12V lead for the EGR, since i dont have one of those.
Voila, I have a MAF again. CEL went off and the car runs better. Plugged in the riv tune and no start still!
Maybe whatever wire the MAF shorted with is keeping the car from starting but i sure as hell cant locate it behind that firewall plug.

I did notice with the bonny tune and the MAF working i still have low boost (5lbs WOT 5krpm) I also only see 5* of timing at that same time so maybe im bleeding off all the boost through the valves. No idea why my timing would be so messed up. Could the sensor wire that shorted be the cam or crank sensor? I would think without those i would have misfires and or a poor running condition/CEL.

I am going to look at the bonny tune again, maybe it didnt copy something over right from the riv tune.

Mr.Riviera wrote:

Tore into the harness again this weekend. 12V+ at the fuse for MAf, nothing at the firewall pin C2.
So i ran a direct wire to the 12V lead for the EGR, since i dont have one of those.
Voila, I have a MAF again. CEL went off and the car runs better. Plugged in the riv tune and no start still!
Maybe whatever wire the MAF shorted with is keeping the car from starting but i sure as hell cant locate it behind that firewall plug.

I did notice with the bonny tune and the MAF working i still have low boost (5lbs WOT 5krpm) I also only see 5* of timing at that same time so maybe im bleeding off all the boost through the valves. No idea why my timing would be so messed up. Could the sensor wire that shorted be the cam or crank sensor? I would think without those i would have misfires and or a poor running condition/CEL.

I am going to look at the bonny tune again, maybe it didnt copy something over right from the riv tune.

why don't you have an EGR?

albertj wrote:

Mr.Riviera wrote:

Tore into the harness again this weekend. 12V+ at the fuse for MAf, nothing at the firewall pin C2.
So i ran a direct wire to the 12V lead for the EGR, since i dont have one of those.
Voila, I have a MAF again. CEL went off and the car runs better. Plugged in the riv tune and no start still!
Maybe whatever wire the MAF shorted with is keeping the car from starting but i sure as hell cant locate it behind that firewall plug.

I did notice with the bonny tune and the MAF working i still have low boost (5lbs WOT 5krpm) I also only see 5* of timing at that same time so maybe im bleeding off all the boost through the valves. No idea why my timing would be so messed up. Could the sensor wire that shorted be the cam or crank sensor? I would think without those i would have misfires and or a poor running condition/CEL.

I am going to look at the bonny tune again, maybe it didnt copy something over right from the riv tune.

why don't you have an EGR?

Stage 4 weight reduction.

Actually the pipe for it developed a hole a long time ago and i just got rid of the system. Plus the intercooler stay cleaner with no EGR and no PCV (just breather).

Mr.Riviera wrote:

albertj wrote:

Mr.Riviera wrote:

Tore into the harness again this weekend. 12V+ at the fuse for MAf, nothing at the firewall pin C2.
So i ran a direct wire to the 12V lead for the EGR, since i dont have one of those.
Voila, I have a MAF again. CEL went off and the car runs better. Plugged in the riv tune and no start still!
Maybe whatever wire the MAF shorted with is keeping the car from starting but i sure as hell cant locate it behind that firewall plug.

I did notice with the bonny tune and the MAF working i still have low boost (5lbs WOT 5krpm) I also only see 5* of timing at that same time so maybe im bleeding off all the boost through the valves. No idea why my timing would be so messed up. Could the sensor wire that shorted be the cam or crank sensor? I would think without those i would have misfires and or a poor running condition/CEL.

I am going to look at the bonny tune again, maybe it didnt copy something over right from the riv tune.

why don't you have an EGR?

Stage 4 weight reduction.

Actually the pipe for it developed a hole a long time ago and i just got rid of the system. Plus the intercooler stay cleaner with no EGR and no PCV (just breather).

So your tune is set up to fake/eliminate the EGR check?

Yes the code is removed, same for the cat.

Swapped out the ignition switch with one from a low mileage riv. Still will not start with the riv pcm.

Edit: something else i discovered...The bonny tune is for a L36 car, not L67. The PCM numbers are the same so the 256k storage and hardware will be the same but the software is different which is likely why the car runs poopy even with my L67 files copied over.

When i tried to start the car with the original riv PCM i noticed the CEL doesnt do its startup check. Going to try to reflash a riv file to the "good" PCM again. Even though the "bad" pcm with the bonny file did start the car.

Swapped files and pcms around a couple times and every time it will do the CEL self check and car will crank with the l36 files. Nada with the l67 riv files. WTF is going on with my car? I'm out of parts to replace.

...any way to compare the L36 to the L67 startup sequence? Anybody?

Still no start as a riv. Been driving it as a L36 bonneville and it is slow as shit and gets 12mpg, but runs with no check engine light.

I had a thought and wanted to run it by to see if it was even plausible...What if the MAF power wire between fuse box and firewall shorted with a PCM power wire. One that would go hot with key on or run. The PCM has multiple power and ground wires, so its able to get power and turn on, but with the riv software its not getting power to right area to turn on injectors or CEL, but with bonny file it can? Seems really far fetched since software and hardware dont normally work like that.
Another theory is maybe a transmission wire that tells PCM what gear its in, so the car thinks its in 3rd and wont give startup sequence. But the bonny has same trans, so would think the wire would be the same.
I keep trying to find a place to take it to but cant find a good shop down here that has the time to do this level of diagnostics.

Mr.Riviera wrote:

Still no start as a riv. Been driving it as a L36 bonneville and it is slow as shit and gets 12mpg, but runs with no check engine light.

I had a thought and wanted to run it by to see if it was even plausible...What if the MAF power wire between fuse box and firewall shorted with a PCM power wire. One that would go hot with key on or run. The PCM has multiple power and ground wires, so its able to get power and turn on, but with the riv software its not getting power to right area to turn on injectors or CEL, but with bonny file it can? Seems really far fetched since software and hardware dont normally work like that.
Another theory is maybe a transmission wire that tells PCM what gear its in, so the car thinks its in 3rd and wont give startup sequence. But the bonny has same trans, so would think the wire would be the same.
I keep trying to find a place to take it to but cant find a good shop down here that has the time to do this level of diagnostics.

can't help with this without comparing those startup sequences... apologies.

So I replaced the wire harness with one I got from a guy on here. Car started up with the riv pcm. I flashed over my old tune onto the other pcm and it runs as well. So no idea what wire had broken but it's back!
Something is still not right though. Car has a hard time idling, and when I get on the gas at all the car stalls out.
Scanning I see boost reads 9.8 or 10.0 all the time, regardless of rpm. If I unplug the MAP sensor it reads -27psi. There is a splice point on the MAP and I show ohm across all 3 wires to that point. There is vac at the connector.
No check engine light, no vac leaks.
If I get the car moving it gets better and mostly drive like normal with full power. Come to a stop and get back on the gas and it will stall.
EDIT:
Driving to work this morning i was able to keep the car from stalling if i take off slowly and dont jab the throttle. Once moving it acts perfectly fine.
Scanning i see IAC moving between 117 and 0 as i think it should. Boost was reading -27 as if the MAP was unplugged. Still no CEL. TPS is responding, MAF shows change, O2 fluctuates. LTFT is pretty much always -17 to -22 so running super rich but maybe the car needs to do some learning.

Mr.Riviera wrote:

So I replaced the wire harness with one I got from a guy on here. Car started up with the riv pcm.    I flashed over my old tune onto the other pcm and it runs as well. So no idea what wire had broken but it's back!
Something is still not right though. Car has a hard time idling, and when I get on the gas at all the car stalls out.
Scanning I see boost reads 9.8 or 10.0 all the time, regardless of rpm. If I unplug the MAP sensor it reads -27psi. There is a splice point on the MAP and I show ohm across all 3 wires to that point. There is vac at the connector.
No check engine light, no vac leaks.
If I get the car moving it gets better and mostly drive like normal with full power. Come to a stop and get back on the gas and it will stall.
EDIT:
Driving to work this morning i was able to keep the car from stalling if i take off slowly and dont jab the throttle. Once moving it acts perfectly fine.
Scanning i see IAC moving between 117 and 0 as i think it should. Boost was reading -27 as if the MAP was unplugged. Still no CEL. TPS is responding, MAF shows change, O2 fluctuates. LTFT is pretty much always -17 to -22 so running super rich but maybe the car needs to do some learning.

Could be that when you were running rich all that time the IAC and TB got cruddy. When's last time you cleaned them?

They are very clean. I have no EGR, no PCV, and no coolant up there so they stay clean. They were also cleaned when the new motor went in last year <10k miles ago.

I got a MAP sensor from autozone and it reads the same and acts the same. maybe i have a bad ground for this sensor? going to check for 5v to the sensor after work.

Think the map sensor was wired wrong. Testing 5v on center wire and think it should be on end