96 850 NA AT Serious Lack ofPower.

Post by **Ozark Lee** » 23 Oct 2011, 01:27

The EGR temp sensor is in the base of the EGR valve - it is the only thing that electrical lines going to it since the EGR valve itself is vacuum controlled. The more I read this post the more it sounds like a massive un-metered air leak.

The EGR valve and the EGR temp sensor are a major pain to get to which, as I think about things, if the EGR valve was stuck open it might also cause your symptoms. Most of the EGR problems we have are with the hole on the intake manifold between the EGR valve and the intake getting clogged up but if the valve was stuck open all then time it is trying to re-burn exhaust rather than air.

...Lee

Post by **confused_al** » 23 Oct 2011, 08:26

EGR in a 96 n/a? Unlikely...but if you do here is how,

http://volvospeed.com/volvo_repairs_how ... n_egr.html

waynej · Post by **waynej** » 23 Oct 2011, 11:09

Thanks guys, Turns out I do not have EGR even though I got a code for it a few weeks ago. I have something that looks like an EGR valve at the back of the engine above the exhaust manifold. After looking closer I see it allows air to be pumped into the exhaust manifold.
I have checked for vacuum leaks but will check again at higher RPM. Is there a sensor for intake air temp? If so where is it? What about coolant temp sensor? I see a sensor on thermostat housing, don't know if it is for ECU or gauges or both.

Post by **erikv11** » 23 Oct 2011, 13:11

That is the SAS (Secondary Air System) valve on top of the manifold, hooks to the air pump under the battery as you discovered. EGR/SAS Confused me for a couple years too, my car came with SAS no EGR. SAS is another weak spot on these cars; when it goes bad consider deleting the system.

I don't think there is an air intake sensor.

The ECT sensor, in the thermostat housing, sends the same info to both the gauge and the ECU. A bad one can cause some weird symptoms/problems without throwing codes, though most frequently the dash gauge starts doing crazy things. I have definitely seen resistance values posted for troubleshooting the ECT sensor, you might be able to dig them up by searching. Might be worth checking its connector, too.

waynej · Post by **waynej** » 23 Oct 2011, 14:04

Erik, Have you or anyone you know deleted the SAS system? It seems to me that these engines are set to run a bit richer than necessary. Without the air I would be concerned about the CAT plugging with carbon. What is the best way to delete the SAS? While trying to fix my lack of power I blocked the vacuum to the SAS valve and the problem got worse.

Post by **erikv11** » 23 Oct 2011, 15:48

Yes, I deleted the SAS system and have seen no codes since the delete. SAS only works at startup I think, and is irrelevant when the car is warm. For sure it is considered to be purely an emissions gimmick that as used on just a few model years.

There was a flurry of "SAS delete" posts over the last year or so. Very fast modification, literally like 30 minutes, you just have to splice in a $1 diode. You can find posts here at MVS, but the best and definitive post is over at Volvospeed.

http://volvospeed.com/vs_forum/topic/14 ... with-pics/

Look at the first post or two, it tells you how to get it done right (I tapped into the wires rather than soldered). Then read on if you wish to learn more about it.

Once the valve is removed, plug the manifold and remove all of the vacuum to the system, even get rid of the pump. You will see from the thread - relays and electronic valve must remain in. Frees up a little space under the hood.

waynej · Post by **waynej** » 23 Oct 2011, 15:57

This problem has been showing up at lower RPM all the time. When it got down to 2400 RPM I could feel a miss (just as Lee said earlier). I checked the plug wires that had been replaced a year earlier and one was bad already.Replaced it with one from the previous set and checked the plugs that I thought I had also replaced earlier. Apparently I had not, they were in very well worn. It's amazing it still ran. Installed new plugs, put everything back together and did a test drive. More power but still the RPM limit (3000 in 1st gear, 2500 in 2nd and something less in 3rd.

Anyone have any ideas? The problem seems to be temperature dependent but this car has no intake air temp sensor and the coolant temp sensor appears to be ok. Is there an outside air temp sensor or any other kind of temp sensor?

waynej · Post by **waynej** » 23 Oct 2011, 19:11

Checked the cam timing - everything right on. Replaced the coil- no difference. Checked again for vacuum leaks - nothing.
There was also a suggestion to check the exhaust to see if the cat was ok. I held my hand in front of the exhaust pipe and it felt normal, even compared it to another 850. Had the wife rev it to 2k,3k and 4k rpm. Immediately felt more velocity each time. Is this a good check? Is there any other way to check?
Anyone have any other ideas.

Post by **Ozark Lee** » 23 Oct 2011, 21:18

We are to the point where we need some compression readings. You can pick up a crappy compression gauge at Harbor Freight for under $30.00 which is much less than you will pay to have a shop do it for you.

The raw numbers may or may not be accurate but the differential between cylinders will tell us much.

...Lee

waynej · Post by **waynej** » 24 Oct 2011, 12:12

Here's the compression (dry) #'s 152,157,155,148,150. The car has 131k miles and uses almost no oil. Been running Mobile 1 High Mileage 10-40 since I've had it. Sometimes, instead of just going up to the RPM limit and holding there, it will cycle back and forth by 50 or 100 RPM as if it is running out of fuel or weak spark. This is rare in 1st. but does it sometimes in 2nd and more often in 3rd. This morning it was only 40 degrees out and I got it up to 3300 RPM in 1st. and 2550 in second! It might run fine at 20 below.

96 850 NA AT Serious Lack ofPower.

Re: 96 850 NA AT Serious Lack ofPower.