Owned my 94 turbo for a few years now. Always used the forums to help out but cant seem to find anything anywhere on my current issue, thus my first post. Here is my question.

I have been getting a code 315 evap system for quite some time. The car runs fine but am jus trying to get all the codes out of the way. So today I started looking into the EVAP system. I recently replaced all the vac hoses in the engine bay so thats one less thing that might be causing the code. I then thought well maybe one of the lines on the charcoal canister is cracked, I didnt replace any of these lines. So i crawled under the car and felt the 2 lines running to it. They seemed fine but after feeling around I found another barb on top of the canister with nothing attached to it and no cap?!?! I started up the car and felt by the barb and could hear and feel vacuum from the barb. I put my finger over the barb to block it off and the car started to sputter for a few seconds but the idle eventually stabalized so I had the girlfriend rev the engine a bit and it seemed ok but stumbled again when it idled.

Is this barb supposed to be blocked or open? If its supposed to be blocked then what could be causing the idle issue when its blocked. Like I said the car runs and idles very smooth with it open as it is.

One side note, sometimes after filling up the gas tank, the car stumbles for a bit when starting it up at the gas pump, and also has similar symptoms in the summer on hot days when the car sits in the parking lot while im at work. It stumbles on first start up for a few seconds then runs fine. Seems to me like all this is related. Any info on any of this would be great. I dont just wanna start throwing parts at it until Im sure what the problem is.

 

I have found that if you use the smoke machine on the EVAP system the crack could be so small and can't be seen with the naked eye. I just had this problem on my S80 it kept throwing code on EVAP. The crack wasn't even bigger than my finger. Download the Volvo Vadis and it will tell you where and how to fix what you need too. And if something should be attached or not.

 

Ive already looked at the Volvo Vadis and the picture isnt very clear. It only has 2 hoses visible on the top of the canister, doesnt show a 3rd barb or hose.

 

Update on this situation. I capped the open barb on the charcoal canister, started up the car and let the ecu relearn without the massive vacuum leak. Car runs great. Found the vacuum diagram on the hood and it shows the 3rd barb not connected to anything so it must be capped. I never noticed the diagram sticker before though, white sticker on white hood, haha.

No onto the new problem. I recently did some work on the car. Replaced the fuel pump due to failure, replaced Fuel pump relay last year, replaced the FPR (gas smell in vac line), new oem volvo plugs, replaced every vac line in the engine bay, replaced PCV system and cleaned PTC, cleaned the IAC and TB along with seafoaming the intake system, new airfilter, flushed tranny fluid. Plugwires, cap, rotor were all replaced by previous owner about 35k miles ago.

Car was running great then the water pump died on me and started pouring out coolant. So I had to replace that and since it was due I replaced the timing belt and tensioner, along with the serp belt, also replaced the heater core since it has been leaking for a while and the system was already drained so I figured why not do it all at once.

The car ran fine for about a week or so then the other day I started getting a lumpy idle on start up. It will rev up like always on start, then start "hunting" for a steady idle between 500-1200. It does this for about 5-10 seconds, almost seems like it might stall until it settles on 1000 and then idles fine. The car then runs fine, doesnt sputter at all or while coming to a stop. But I can shut the car off, immediately restart it and it goes through this cycle again.

I tried cleaning the contact on the ECU and Trans ECU, nothing. I tried disconnecting the MAF sensor and the car runs horribly and idles all over the place, runs fine connected, so MAF is good. Tried disconnecting the TPS and nothing really changes at idle. I also felt for a "click" from the TPS when opening throttle but didnt feel anything.

Im thinking the TPS is bad due to this and also a boost issue that I cant figure out and the TPS is involved in controlling boost. Anyone have any ideas or think the TPS might be the root to bothe the idle and boost issues. Sometimes when I press the throttle it seems like nothing is happening, then all of the sudden the car comes to life, like the TPS wasnt sending the right signal then all of the sudden it does.

 

Also I am still getting the 315 EVAP code after capping the open barn on the charcoal canister so it must be the purge valve. I did go back over all the vac lines and all are still connected.

My boost issue is a lack of boost all together, barely a quarter into the white on the gauge. I pulled the line from the wastegate and it builds boost super fast and runs like a beast so the wastegate is working right, gauge goes all the way to end of white. I replaced the stock BCS with the Delco solenoid, this seemed to help build a bit more boost but im still not making full boost. I did a boost leak test and found the CBV diaphram to be bad, replaced that and no more boost leaks. Boost still builds very slow and when it hits 1/2 to 3/4(full boost stock) on the gauge it holds for a second then drops off to barely in the white. Its almost like the ecu cuts the boost for some reason.

My guess again is the TPS because the ecu caculates boost from the MAF, TPS, and speed signal. The MAF checked out good.

Also Im not getting codes for anything related to any of this. Only the 315 code, and a 143 code, front knock sensor which I have always gotten since I owned the car. It still has the old knock sensors that have the connectors on them. I cleaned the terminals while doing the pcv system and put some dielectric grease on the connectors hoping this would help but didnt. I guess one of these days I will get the upgrade kit and replace them.

Any help is appreciated.

 

Just for reference, the car is a 94 850 turbo with about 165k.

 

Why don't you ck the TPS with an Ohmmeter?

If it were me, i wouldn't neglect that knock sensor fault either!

 

I was going to do that today, but last night I was looking around under the hood and noticed that the vac line for the boost gauge has a small rubber piece connecting 2 hard lines, it was under the intercooler pipe, it was very loose. I replaced the rubber piece and also the elbow on the vac tree and problem solved.

Eventually I will get around to replacing the knock sensor, but it comes and goes, sometimes it takes a month or so for the code to come back. I just hate the idea of pulling the intake manifold off again.