Turbo not working-1994 850, 150k +

fasttaxi · Post by **fasttaxi** » 24 Jun 2008, 06:58

I'm new to this site. I have a sick volvo, with 170 K miles let me tell you.
This vehicle is being used as a taxi, we bought it used last fall, Amazing huh !
I believe the turbo is lubed and cooled by the engine oil, the intercooler is at the front of the car by the raditor. I think the turbo unit rotates from exhaust pressure, and the actual air blast into the intake is activated by vacuum controls. I also believe the boost gauge is actually a vacuum gauge.
The vehicle idles nice and under light throttle it performs well. When trying to accelate up slight inclines or getting into traffic quickly it acts just like a non-turbo and the boost gauge is pointing to the middle, and doesn't move even when the engine is off.
The volvo has gotten horrible fuel mileage for months, best ever was arround 18 on the highway at light throtle 50-55, however the turbo was working great whenever more than slight throttle was given.

The engine has new sparks plugs, gas and air filter(which was totally filty).

Where should I start to trouble shoot the problem ? I believe the obd connector is under the coin holder in front of the shifter. My vehicle is a 94
would that be obd 1 or 2 ? Should I get the codes first, or try some simple visual search or clean-up.
What effect if any would a dirty airfilter have on anything that might cause a temporary malfunction to the turbo unit?
I was unaware that the contol module box also had a filter, but volvo is an extraodinary vehicle for sure. I will check and replace that if needed.

Post by **MadeInJapan** » 24 Jun 2008, 07:14

First I would like to welcome you to MVS. I think you are the first one to use the 850 as a Taxi here and I personally would like to hear about how your car holds up under such constant use and high miles. Be aware that a car in use such as your own will need more frequent maintenance such as oil changes, PCV replacements and transmission flushes (exchanges of fluid). Now let's get to the matter of your specific questions and issues.

All of your assumptions are correct....but the OBD port on a '94 is most likely not a true OBD-II. At least in the U.S., it wasn't until '96 that this became a reality. Most likely you have a set of 2 diagnostic ports under your hood, just to the right of the windshield washer tank. See this diagram and explanation: http://volvospeed.com/Repair/a2.html which tells you how to read your engine codes and to reset them. Our repair database also has a fault code library here that should be helpful to you: https://www.matthewsvolvosite.com/chat/p ... hp?t=10758
You reset the codes after reading everyone in every port mentioned. Read them all and write them all down for whichever port and we'll try to help you trouble shoot your problems. Btw, the SRI (service reminder indicator) light can be reset by doing the following: http://volvospeed.com/850slight.php

Reading the fault codes is the only real way to get you moving in the right direction of solving your Volvo's troubles, but I suspect a vacuum leak or worse some vacuum leaks for your turbo to not spool up at full boost. Even if the vacuum hose that your boost gauge is connected to (under the throttle cable cover, you will find a "vacuum tree" with many lines connected- one being your boost gauge line) has a leak it would cause enough vacuum loss for your turbo to not spool up efficiently. Otherwise, you could have a leak in one of your larger intercooler hoses from the turbo onward to and from your intercooler.....so check all of those. You will hear a "sucking sound" if this is the case even with the car at idle and the hood up. Oh, and yes, a dirty air filter can cause inefficiency with gas usage.

Good luck and let us know how you do!

Regards,
MIJ

fasttaxi · Post by **fasttaxi** » 26 Jun 2008, 07:58

Thanx MIJ

I found a discounted vacuum line in the front of the battery. The turbo gauge and actual boost is working. The codes are 232, 315, 233. Is there an adjustment to the idle trim. What would be the first thing to check on evap system? gas cap ? The engine runs much better, but has a little skip, not bad just not as smooth as I think it could be. The plugs were changed about 2-3 weeks ago by a defective back yard guy. Probably never set the gap proper, just trew them in out of the box! I think Iread someones warning about this and the results. What is the proper gap ?

Thanks again you all your help
Fasttaxi

Post by **MadeInJapan** » 26 Jun 2008, 14:56

Yes, change the gap...if a turbo you're suppose to go 0.028 inches or less...try 0.026 on each (you're using it as a taxi)...also, .. AFter that, for ignition, it would be the wires and rotor/cap. Btw, what kind of plugs did he put in? If you have to get the wire set, avoid Bosh...get OEM Bougicord wires. The other stuff is fine w/ Bosch, except Bosch platinum plugs...just get the copper cores.

Yes, the gas cap first (look at it to be sure the rubber seal is good and click it shut with several clicks). If you still get the Evap. codes, then you need to investigate further...maybe a bad purge valve (it's up on the front top of the fan shroud at the front of the car and has a line running in and a line running out). After that the actual vacuum line and/or Evap. Canister that sits in the front wheel well.

fasttaxi · Post by **fasttaxi** » 27 Jun 2008, 07:57

94 -850 turbo
The guy put the cheapest plugs in right out of the box. the vehicle is getting only 14-15 mpg and has a minor skip. I found a vacuum line discounted by the right fender, the vacuum size line is a part of lines going to a small clear filter that looks like an inline gas filter. These line have a few straight and T fittings and numeous hoses going everywhere, two down under, one behaind the radiator, one to what looks like a canister filter with larger hoses connected to it. I believe it's all part of the evap system. Is this filter just a simple gas type filter or (let me guess) one that should have silca moist asborbing crystals of something. Napa didn't list one. Is that filter a maintennance wearout item and exclusively a volvo part ? Please inform if you know.
correct plugs (non-plat), copper core nkg plugs with .026-28 gap being installed today.
BTW; the taxi company owner almost crushed this beauty, because of clunking when shifting into gear from stop and vibration under throttle, and after $800 in front end and rear joints and bushings. I finally took the car and checked the CV joint and axle and found it was about to fall apart, and had it fixed with a tranny flush for $250. I wish wasn't such a woos I and bought the car myself for $300.
Never trust a dishonest or stupid uninformed mechanic.

fasttaxi is a little faster now

Post by **MadeInJapan** » 27 Jun 2008, 11:50

Glad you're getting things sorted...normally the Charcoal cannister under the fender is not a wear item, but they can get completely filled and clogged up...I would re-attach the hose to it and make sure the others are good...all the way up the the purge valve on the fan shroud...from there, there is a one way locking valve that allows only for the gas fumes to be plumbed back in to the manifold via the vacuum tree...I would think that reattaching the line that was loose and driving the car for awhile will fix itself. Good luck and let's hope there are no more evap/vacuum line leaks.

fasttaxi · Post by **fasttaxi** » 03 Jul 2008, 21:24

Thanx MIJ

I finally got the Bosch cap and rotor replaced, BTW napa only stocks eklin steel contacts and had to special order the Bosch. The cap had a crack and I assume that was causing the slight misfire. Now the engine runs smooth , but the turbo boost is not what it use to be. Very slow off the start and turbo gauge does move to much more than half way until the trottle is nailed and than only to less than 3/4 even at 4k rpm. The car use to leap when to turbo kicked in around more than slight trottle and 1500 rpm.

Codes are 233 and 315, I read evap system, also idle air trim exceeds control limits.

I found a valve, looks like a 3 vacuum hose connector check valve, under the battery tray, that has an open fitting w/one connector missing a hose to it. Is that part a maintennance wear out part, or should I just figure where the hose is and reconnect it? Could you tell me if that might have something to do with low turbo boost.

I found what looks to me like a EGR valve behind the engine with a rod coming out it, is this the EGR valve? I assume the rod goes to the actual turbo unit. The rod does move when I open the trottle some, is the waste gate in the turbo unit at the other end of the rod ?

I read some rod is adjustable to increase boost, is this the rod ? And is this ajustment needed because of a worn diaphram or EGR valve.

I might be off base to my thoughts about this, please help to confirm or correct my thoughts on this matter.

Thanks
Fasttaxi
smoother Taxi, but still not fast enough Taxi

Post by **MadeInJapan** » 04 Jul 2008, 11:18

What you found under the battery tray is the cruise control hoses and pump. There is suppose to be one open so it's best to leave it alone. On the side of the air filter box is the turbo control valve (TCV). Make sure that all of the small hoses (3 of them) are connected up and the TCV is plugged in to the electrical connector. If that's not it, then one turn on the turbo wastegate rod might help you....make sure also that there are no leaks in the turbo hoses. Wish I could help more but I'm at the beach until 7-12 and don't really have much in terms of my diagnostic software, etc. here....also using my cellphone to connect to the internet- absolutely no wireless hotspots nearby that I've been able to find.

fasttaxi · Post by **fasttaxi** » 09 Jul 2008, 18:58

The power brake boost quit working. A basic pedal pressure vacuum leak down test, shows the booster working but not holding vaccum after engine shut off. I chanced the easiest task of replacing the check valve,I found the old valve to be blown through from the inside out like would be a straw. The used different valve (off a chevy P-UP) seemed to hold much more pressure, so I plugged it in. My thought is the original check had leaked vacuum enough that under trottle the turbo didn't have enough to function properly.
The car was driven with a bad working turbo about 250-300 miles and the brakes went. After the plugs, cap and rotor were put in it ran, but 11 MPG and was a dog off the line. Now the car skips and the idle vacuum is between 16-17 psi. Would the computer change the timing to compensate for the now again fouled plugs. Or maybe the booster or valve is still leaking slight vacuum at idle.

I'm changing the plugs. My question is how to reset the computer to readjust to proper timing, and if that could be the problem of barely running now.

Post by **MadeInJapan** » 09 Jul 2008, 20:52

In your case, I think unplugging the battery for 20 minutes or so would do the trick and reset all of your adaptives. Some people say to disconnect it and then push down on the brake pedal to discharge any left over current. If you do this and have a Volvo radio in your 850 make sure you have the radio code.