SVX can't climb hills - Page 6

1986nate · #76 02-21-2014, 05:57 PM

92's don't throw the CEL unless they're pretty much dead. You can even disconnect the MAF and it takes it like 5 minutes to trigger. They were designed NOT to have any warning lights come on in the 92's.

WhatIsThisIDont · #77 02-21-2014, 07:21 PM

You guys have been great through this. It does climb hills, it just seems coincidence that it died on the hills the first few times. For the first miles of driving, it will handle everything normally, and then fall later.

It's been sitting all week, so I went out tonight to make sure it would start in prep for it's little trip tomorrow, and it starts fantastically the first time. I then shut it off immediately and restarted. On the restart, it only rev'd to 1200 rpm rather than the normal 1800 or so it revs to for a split second on cold start. It rev'd to 1200, coughed for a few seconds, and then up rev'd to normal speeds.

Tomorrow is the big day that we start looking at it more in depth (Thanks again, Nate) so we may have some answers tomorrow night.

I have to bring her home for spring break in two weeks, and I have a lady waiting for me back home, so you could say I'm starting to get motivated

I'll let you guys know more tomorrow.

Chucksta · #78 02-21-2014, 09:11 PM

Knew I forgot something...

A bad cam angle sensor will also mimic these symptoms.

If you've seem temperature swings that weren't possible.. a bad temp sensor will give the ECU enough bad intel to make stoopid stuff happen..

Tapani · #79 02-21-2014, 10:11 PM

One thing which happened to me once: The torque control signal from the TCU..... a bad connection in the QC wiring caused a massive misfire - and only happened when going up a hill

I guess the harness moved a little from the change in gravity direction. Scared the

out of me.

I can not remember by heart if the signal is 5V normally and then goes to 0V when the torque control is activated (during shifts) or vice versa.

Get the Evoscan, you can monitor the switches too.

/T

THE NEW GUY · #80 02-22-2014, 06:25 PM

[QUOTE=Chucksta;732226]

But, I'd still like a good explanation / tutorial about the high pressure in the gas tank.

[QUOTE]

The pressure in the gas tank is negative. (read vacuum)
The ECU send pulses to a solenoid connecting the intake vacuum to the canister and to the gas tank. This is done under certain conditions only, not all the time. You will notice a periodic click sound under the intake (passenger side) one minute after starting the engine, at about 1 click every sec. The goal is to use the gas fumes in the tank.
Jose Carlos

WhatIsThisIDont · #81 02-22-2014, 07:55 PM

I went to see Nate today and the decision is it's the cats. I always thought my exhaust looked a little weird and different, but didn't think much of it.

Guess who's cats have been replaced with aftermarket fun boxes!

Tomorrow, I can finally crawl under and at least open the piping up to get her on her feet, with replacement cats to be an ASAP deal. After that, life should be back to normal.

Worst case scenario is I'll replace some exhaust that needed it anyway

This car seems to know about my to do list and didn't think I was doing it quickly enough.

Chucksta · #82 02-22-2014, 07:58 PM

Not to hijack.. but thanks for the explanation! I wasn't kidding when I said I knew Jack about that... All this time, I thought it was PRESSURE escaping... DUUUHHHHH... Thinking about it for a bit, that makes perfect sense. If it would have been pressure, I would have smelled gas fumes every time I cracked the cap when refueling! That's would be why a bad gas cap triggers a CEL ( at least on OBD 2 ).. And why a high negative vacuum would negatively impact the fuel pressure at the rail. If there's no vacuum, it senses it and throws a code.. So it's kinda like a EGR, just for the fuel tank.

Since we can't embed sound clips.

.. Mine goes FFFTT... The OP's goes WWWWHHHHOOOOOSSSSSSHHHH!... Although it has been proven that the high negative pressure is not the issue ( determined by driving with the gas cap not screwed on tight), it would still seem to indicate an issue in that system, as in possibly the solenoid being stuck open. If nothing else, that's at least one more clue..

Thank you "New Guy" for a great, brief, and sound (pun intended) explanation.

Now... Back to our regularly scheduled programming....

EDIT..

Previous posted while i was typing.. LOL..

Glad you found it!! WHOOHOO!

Please post when she's running like she should!

Blacky · #83 02-23-2014, 06:01 AM

Please let it be over. Please make it stop!

WhatIsThisIDont · #84 02-23-2014, 09:37 AM

Quote:

Originally Posted by Chucksta

Not to hijack.. but thanks for the explanation! I wasn't kidding when I said I knew Jack about that... All this time, I thought it was PRESSURE escaping... DUUUHHHHH...

I actually didn't know that either. That's wickedly awesome!

Quote:

Originally Posted by Blacky

Please let it be over. Please make it stop!

Here's hoping. If it fires up and works correctly with ventilation before the cats today, I'm buying a victory cigar and enjoying it very thoroughly.

NiftySVX · #85 02-23-2014, 04:36 PM

Sorry I didn't keep up with this better. I am so glad that you had that vacuum gauge on there. The slow return to normal vac is again a clear cut sign of engine breathing problems. I am glad you got a diagnosis!

Like I said exhaust restrictions due to a failed catalyst can be tricky. You would think it would slowly build pressure until it starts to run bad, but it is sometimes random in how it acts.

I had forgotten to ask if the exhaust note sounded normal or not. And for the record to anyone who is reading this the method of pumping the gas into a jar and checking for water is the best way to do it, any good mechanic will have a glass jar on hand for this purpose.

I would suggest careful inspection of the intake and EGR systems on your car when it undergoes repair. An exhaust restriction can cause damage to valves and other parts but I would think you caught it in time.

And to those who asked about a drain on the tank, no it is a multi layer fiberglass/plastic/etc unit (seven layers IIRC?) that is puncture and fire resistant. EDIT: (implied but not stated) There is no drain it is common to use the pump to pump out the fuel as others suggested.

Additionally, it is normal for a vehicle of this vintage to have pressure in the fuel system. It is also normal to have a vacuum in the tank due to the removal of fuel from it. There is usually not very much pressure but there can be some substantial vacuum in there. Due to the return of hot fuel from the tank, you will have expansion and that is vented when you release the cap. This is technically not supposed to be the case because the purge solenoid is supposed to vent this vapor to the joke of a canister the SVX uses. I cannot recall if the SVX purge system on OBD I cars routes this back to the intake but I believe that this was a requirement of OBD II. This is obviously HATEFUL to the environment and should be less evident on the OBD II cars as more advanced EVAP systems were part of that regulation, but I have never paid attention to it on a 96 or 97 SVX. Modern vehicles are sophisticated and actually use the charcoal canister and vent this pressure differently, a returnless fuel system, and an active system that includes a circuit for the tank side and for the engine side. They include a vacuum pump and sophisticated sensors, valves, and are self calibrating.

Evaporative emissions can be quite confusing and is one of the most difficult things to understand and diagnose due to the number of different systems. Everyone can be glad that the SVX, for all intents and purposes, does not even have such a system.

One more thing, as Nate mentioned the 92 cars, and indeed all the OBD I cars require some serious issues to turn the light on. The engineers did not like that the car would have a light and were worried the light would come on regularly and the owners wouldn't like it. Even some of the early OBD II cars could have a pretty much dead hole and the light would remain off.

WhatIsThisIDont · #86 02-23-2014, 05:43 PM

So the last 24 hours have been pretty weird.

I was on my way home when she started to cough. No problem. I just shut it off for a while and went on my way. Except this time, it only went 100 feet and choked again. Waiting wasn't helping, and it got to the point where it would start for a few seconds and die. It then would crank with no sign of fire.

I towed it to a nearby family member and we worked on it today. We drilled some holes in the pipes right before each cat. We got it to start, and it sounded good until it went to idle down. It lowered the revs and eventually died. When I tried to start it again, it started and died within a few seconds. Then it will crank again with no signs of fire.

If I let it sit for an hour, it'll start and do the exact same thing.

We went vacuum leak hunting and found another line broken. This one is on the front of the intake's underside on the passenger side, behind the PS pump. So that's on the fix list for when the intake comes off along with every piece of rubber around it.

I can do more diagnostics later this week, but on my diagnostic list so far is:
(Each done separately)
1: Disconnect temp sensor from ECU
2: Disconnect O2 sensors
3: Find a better deity to pray to.

Any more ideas? We have two weeks before I want to take her home for spring break, so failure is not a (very convenient) option.

Thanks guys,

Randy

Chucksta · #87 02-23-2014, 05:50 PM

Re: NiftySVX

Excellent Post! I appreciated the more in depth explanation of the difference between OBD 1 and OBD 2... Nicely put, and I'm sure others appreciated it too.

As I watched this thread grow in length, as obviously so many others did, some silently, some contributing, it was actually great to see this online community pull together and put forth so much effort into "exorcising the demon". Especially as between all the members, there is so obviously a huge body of knowledge regarding the inner workings of, for a vehicle with such low production numbers, the tenacity of all involved was indicative of how tough it was to nail down the elusive demon.

I truly hope Nate nailed it and I'll not only spark up a victory cigar, I'll even browse my FSM while I do so.

EDIT...

DAMN...DAMN... DAMN IT!!!!

I must be psychic.. Or Psycho.. One again we were typing at the same time..

Sir... I am so sorry...

My only suggestion would be what I posted a bit back.. check the crank sensor and cam sensor, if for no other reason than to eliminate them as a possible cause. It's easily and quickly done, all you need is a multi meter. Fortunately, or unfortunately, depending on how you want to look at it, checking them when it won't fire would be more definitive than when it's running..

Damn..

svxfiles · #88 02-23-2014, 05:55 PM

Quote:

Originally Posted by WhatIsThisIDont

So the last 24 hours have been pretty weird.

I was on my way home when she started to cough. No problem. I just shut it off for a while and went on my way. Except this time, it only went 100 feet and choked again. Waiting wasn't helping, and it got to the point where it would start for a few seconds and die. It then would crank with no sign of fire.

I towed it to a nearby family member and we worked on it today. We drilled some holes in the pipes right before each cat. We got it to start, and it sounded good until it went to idle down. It lowered the revs and eventually died. When I tried to start it again, it started and died within a few seconds. Then it will crank again with no signs of fire.

If I let it sit for an hour, it'll start and do the exact same thing.

We went vacuum leak hunting and found another line broken. This one is on the front of the intake's underside on the passenger side, behind the PS pump. So that's on the fix list for when the intake comes off along with every piece of rubber around it.

I can do more diagnostics later this week, but on my diagnostic list so far is:
(Each done separately)
1: Disconnect temp sensor from ECU
2: Disconnect O2 sensors
3: Find a better deity to pray to.Any more ideas? We have two weeks before I want to take her home for spring break, so failure is not a (very convenient) option.

Thanks guys,

Randy

So it's easier to drill out the exhaust system than to remove the O2 sensors?!
Maybe letting the O2 sensors hang in the wind has a deeper meaning than just releasing pressure!

NiftySVX · #89 02-23-2014, 05:59 PM

Quote:

Originally Posted by WhatIsThisIDont

So the last 24 hours have been pretty weird.

I was on my way home when she started to cough. No problem. I just shut it off for a while and went on my way. Except this time, it only went 100 feet and choked again. Waiting wasn't helping, and it got to the point where it would start for a few seconds and die. It then would crank with no sign of fire.

I towed it to a nearby family member and we worked on it today. We drilled some holes in the pipes right before each cat. We got it to start, and it sounded good until it went to idle down. It lowered the revs and eventually died. When I tried to start it again, it started and died within a few seconds. Then it will crank again with no signs of fire.

If I let it sit for an hour, it'll start and do the exact same thing.

We went vacuum leak hunting and found another line broken. This one is on the front of the intake's underside on the passenger side, behind the PS pump. So that's on the fix list for when the intake comes off along with every piece of rubber around it.

I can do more diagnostics later this week, but on my diagnostic list so far is:
(Each done separately)
1: Disconnect temp sensor from ECU
2: Disconnect O2 sensors
3: Find a better deity to pray to.

Any more ideas? We have two weeks before I want to take her home for spring break, so failure is not a (very convenient) option.

Thanks guys,

Randy

Has there been any repair work on the car? I thought that you were having the catalysts replaced? Did that get done?

WhatIsThisIDont · #90 02-23-2014, 06:17 PM

Quote:

Originally Posted by svxfiles

So it's easier to drill out the exhaust system than to remove the O2 sensors?!
Maybe letting the O2 sensors hang in the wind has a deeper meaning than just releasing pressure!

We were so sure that it was clogged cats that it was easier to drill and made more sense at the time. (Read: I am not a smart man) The O2 sensors were also in pretty well and I couldn't get the leverage to get them out, and the Dremel was giving me the seductive eyes

Quote:

Originally Posted by NiftySVX

Has there been any repair work on the car? I thought that you were having the catalysts replaced?

They are definitely being replaced with no question. I was just trying to get it at least drivable until I can get the cats in and get the appointments made.

This was the first time I got a good look at the exhaust after I know what it should look like. My exhaust is straight pipe to about the driver seat, where each side goes into a cat. Then more straight pipe into a homemade Y pipe and into the stock muffler.

I'm assuming the cat(s) are bad because I get a buzz that I thought was the resonator buzz everyone speaks of. It's only now that I realize that I don't have a resonator, so that's out of the question.

Regardless, this piping has some of the worst craftsmanship I've ever seen. It will be replaced soon.

I'll check those crank and cam sensors when I get out there later this week.

On a side note, you guys have been utterly awesome. I owe quite a few of you already.