Time to play "Which sensor's broken?"!!!

[kwren]

Maybe

Keith

[Trevor]

Originally Posted by kwren

If the sputtering reduced the idle rpm substantially, that could lower the voltage output from the alternator... Normally, I think.

Keith

Yes keith,

The cart is before the horse.

Sputtering of the engine will cause the alternator to run slow (P.S. Below normal idle speed.) and beyond the point that it will produce sufficient voltage, so as to be above battery voltage. It is not a case of the alternator getting warm, it is the engine temperature rising to a point whereby the engine falters and as a result the alternator slows and stops charging. ( P.S. On this basis the alternator is not the cause of the problem.)

The fault whatever it is, if it has existed, will be retained in memory. You do not have to even start the engine before reading codes, much less rev it. Check for codes after simply turning on the ignition as per instructions. (P.S. A check on the codes should provide an answer.)

Hooooray, Trevor.

[SVX10]

Originally Posted by kwren

If the sputtering reduced the idle rpm substantially, that could lower the voltage output from the alternator... Normally, I think.

Keith

Yea...that thought occurred to me last night after I posted. I'll check and see which comes first...the low idle or the low voltage. I'll also check it by seeing how it runs while connected to another vehicle via jumper cables. The reason my brain was zeroing in on the alternator was because of what the Autozone guy, of all people, told me. He said that when they run their alternator tests some of them will idle fine and put out the proper voltage, but their procedure is to run them @ 2000RPM under load. He says that some will gradually drop voltage until they don't supply enough to run the vehicle properly. So, if I hook the SVX to a healthy car via cables it should at least change the behavior. That would allow me to at least focus on the charging system for further diagnosis.

BTW, where are the OE alternator grounding points? Still trying to figure out why the car goes dead without that alternator mod cable (alt + to battery +)

[Trevor]

The alternator is bolted to the engine, the engine is grounded, as will be proven by the starter working.

It would appear that when the mod. was carried out, the original wires connected to the main terminal on the alternator were possibly disconnected. This would leave only the alternator to battery wire to complete the required circuit.

Alternatively, the wire battery to fuse box may not be connected to the battery, again breaking a circuit.

Why do you insist that the alternator could be causing an idling problem?

You state in post #1 :-

I pulled the diagnostic connector to see what codes I have, and this is when it got a bit more interesting. As I held the engine at 3000 RPM it would stay there no prob for about 15-20 seconds, then it would completely cut power, RPM would drop, and no response from the a-pedal to revive it. About 1-2 seconds later if I was still on the gas it would respond again for about .5sec, rev up, and then cut out again. If I keep my foot in the gas it'll keep cutting in and out in this sequence seemingly indefinitely. If I let my foot off the gas it will stall.

There is no diagnostic connector to pull (disconnect ?), when checking for codes. If you disconnected something you could have caused your “more interesting” problem.

You also state “The problem starts as the engine gets warm.” Surely this is the route cause of your fault.

I now leave you to it.

[SVX10]

Sorry...didn't pull any connector. Pulled codes. I guess I meant I pulled the connector and wires out from the panel. Didn't actually disconnect anything.

I'm not insisting that the alternator is at fault...just at a bit of a loss and trying to troubleshoot what could be causing my problems. In doing so, I'm thinking about what has changed since it was working properly.

New spark plugs - could crappy plugs cause this (NGK R plugs)?
New timing belt - it's too smooth when it's running for timing to be off. I also triple checked that when I had the engine out for work.
Rebuilt alternator - What are symptoms of failure? Why is the circuit broken when I disconnect the alternator wiring mod + to + cable?
New valve cover, cam, and rear seals - Don't see how these would relate to my problem.

Based on what Auto Zone explained, I feel that I need to check the alternator output voltage while revving. If the voltage isn't steady and trails off even with revs as they said it would if the alternator was bad, then I have a good suspect. I will also try running the vehicle while attached to a jump as that would give me good info as well. The first may show good alternator voltage and the second may have no effect to stalling, but they're both free and easy and will give me confidence in the rebuilt alternator. However, if the alternator shows a voltage drop while revving then it's pretty obvious what's going on, and if the jump keeps the vehicle running smoothly then it's virtually solved. The only question then is why it occurs only when warm.

I cleaned the IAC by removing the TB and spraying with carb cleaner. The AAC valve has been working fine all along. My battery is brand new. It starts great every time and idles fine until it's warm. I can still try the engine temp sensor, but if the alternator doesn't check out, then why spend the $30 on the temp sensor?

Thank goodness I went all in and bought a new daily driver before I did all the work I did on the SVX!

And the engine revving diagnostics are based on the method from the ancient Kinetic Concepts web page document. I pulled the codes from memory and got vehicle speed sensor #2 (33), P switch (51), and N switch (52). If I'm not mistaken, these should all be caused by the MT.

So, thanks for the input, I'm not trying to be stubborn with the alternator. I'm just running out of logical options and the replace and check method gets costly fast.

I'll update after doing some more testing, probably tomorrow night. If anybody has further ideas I'd like to hear them!

[kwren]

Always keep in mind that under certain circumstances some of the codes could be ones stored for a while, could have already been corrected, and not cleared. I haven't time to read everything here today so if this is already covered, sorry!

Keith

[Trevor]

Originally Posted by SVX10

Sorry...didn't pull any connector. Pulled codes. I guess I meant I pulled the connector and wires out from the panel. Didn't actually disconnect anything.


So, thanks for the input, I'm not trying to be stubborn with the alternator. I'm just running out of logical options and the replace and check method gets costly fast.


I'll update after doing some more testing, probably tomorrow night. If anybody has further ideas I'd like to hear them!

O.K. all understood.

Recently I checked for codes on my SVX and got a strange read out. Clearing and second check a couple of days later, produced logical codes.

It could be well worth your while to run a second check as this would not be at all arduous. Give the gremlins the chance of a second opinion.

[SVX10]

OK...got it all figured out

1st - alternator tested OK @ AZ and it also held voltage even as vehicle was sputtering and dying

2nd - I followed the 2 white wires from the alternator into the fuse box and found that my fusible link was actually broken and the car was only running because of the alternator wiring mod + to + wire bypassing the fusible link. Put in a new link and now I don't need the wiring mod to keep power.

3rd - checked my passenger's side coils and plugs to determine why they occasionally misfire. The coils look fine. Plugs look OK, but I'm not sure what to look for. They appear to possibly have some oil on them. Could that be from not doing the valve cover gasket properly, or pinching it or something? I suppose the oil could be flooding the cylinder somewhat causing a misfire. Still not sure on that one

4th - unplugged the engine coolant temp sensor (two wire sensor) and it ran fine. I had noticed that the fans NEVER came on with that plugged in so I figured I'd unplug it and see if anything changed. Well, alot changed. Fans came on and engine didn't stall.


So, Trevor, you win the grand prize! Temperature sensor it is!

[SVX10]

Sad to resurrect this thread, but the stalling has NOT been cured But, a friend at a local shop hooked the SVX up to an OBD1 reader and it gave a crank angle sensor code.

So, could that be the issue? To re-summarize what has happened so far

1. Start and idle cold no problem, but slowly drop RPMs as car warms up eventually stalling once temp is reached
2. Start and idle horribly rough with a random assortment of fuel injectors or spark plugs not working. For example, one time none of the right side bank fuel injectors were working. Turned it off, turned it back on, and all was well. Today none of the spark plugs were working. Turned it off, waited a bit, and turned it back on...all was well.
3. Start and idle cold no problem, begin to stall, but save itself when I unplug the Coolant Temp sensor
4. Start and idle cold no problem, begin to stall, proceed to stall even when I unplug the coolant temp sensor.

As you can see...a random assortment of stall or rough idle scenarios.

Looking for more input...

[SoCal LS-L]

Yeah, absolutely. Check the wiring first though, after I removed my alternator I discovered the insulation right at the CAS connector had become brittle and split open, exposing the bare wire. I fixed it using some brush-on wire insulation before it became a problem. A malfunction with the CAS will DEFINITELY stall your engine... thats gotta be it.

Remove the sensor and inspect it, sometimes they can collect a lot of crap on the magnetic end, you may be able to clean it. From the intermittent nature of your problem, take a close look at the connection too, it seems like theres a hairline fracture of the wiring, or the connector lead, or just a corroded connection.

All in all, there is a 90% probability that this is your problem, so check it, maybe clean it, or replace it if everything else looks good. The ECU is extremely reliant on the CAS for fuel and spark management, as it provides the ECU with the position signal for top-dead-center.

[want-a-fast-svx]

Hmm just a couple thoughts/suggestions. First on newer cars it isnt really recommended to pull the alternator as that can cause a voltage spike that has the potential to blow circuits, fuses, or various electrical components that dont like spikes in voltage. This is more precautionary than anything but felt it would be good to state.


2nd- As has been stated the CAS would definitely account for your problems.

3rd- Have you tried inspecting and testing the MAF? What about cleaning it with MAF cleaner?

4th- I for the longest time had a bypass air control solenoid code on the old engine and it would cause poor idle, and random stalling. Something to think about but prob. not your issue.

5th- When i put the most recent engine in the pass. side bank of injectors were not injecting fuel. The injectors were clogged and tapping on them while the engine was barely running cleared them out. Again prob. not your problem but not hard at all to tap the injector while its running to see if it changes anything.

6th- I believe a while ago someone was battling the electrical connector in the center of the firewall that sends the signal to each side of the engine for either fuel or spark cant remember.

Little long winded but I figured it couldnt hurt to give some suggestions as I know how crappy it is to deal with this. I am guessing you are a 5spd. Have you got a lightened flywheel or is it stock? Just a thought that with a lightened one like i have if you come off the gas totally quickly it will just barely catch the rpms in time to stop it from stalling. I tweaked my driving habits and got the stall issue much more in control. Again sorry for the length. Good luck with your search

[want-a-fast-svx]

also, do you have a digital multi-meter? If not that is a very valuable tool to have in general and especially on these cars as they are getting to the age that wires are gonna start getting very brittle.

[NiftySVX]

Check the ground on the back of the manifold!
double check it

A way left field but possible cause for these systems could be restricted exhaust. It's almost textbook symptoms of it. You could have a plugged cat or something. It's highly unlikely but possible.

Just giving new ideas.

Also, I have never seen an SVX with an ECT failure (i know it happens, I just haven't seen it) but i've seen a bunch of 2.2l cars do it and usually they had a MIL on and they would be hard to start cold, and the fans would run at high speed at any time the IGN was on or run.

Good luck!

[SVX10]

Thanks for all of the input everybody.

Next question...which of these would still allow the engine to run smoothly sometimes. Today I started it and it ran great until it got up to temp...then it stalled. Seems like the exhaust, grounds, injectors, and other hardware issues wouldn't allow it to ever run right. This leaves me thinking sensor (maf, crank, cam) or possibly intermittent wiring issue.

Probalby gonna bite the big one and order the crank and cam sensor

[want-a-fast-svx]

Hmm... I would clean the maf, get a multimeter and try to test the sensors out before you start to throw parts at it. Just my .02.