1996 850 Turbo, Rough idle, new PCV didn't fix it...

futureboycolin · Post by **futureboycolin** » 04 Oct 2013, 22:20

Seafoamed the engine today, cleaned the IAC and the throttle body.

Boy am I an idiot...forgot to plug the TCV back in. Did so and the P0245 is gone. The P0102 code is also gone since I reinstalled that vacuum hose and cleaned the MAF. Checked the cap and rotor, didn't seem all that dirty. The #1 plug was blackened again, but didn't smell like fuel. Also noticed that the #5 plug was a bit fouled. Still have yet to order a new set of NGK's from Amazon - Pepboys doesn't have them.

I didn't mess with the EGR, because I ran out of time, but on the way home from work tonight I took the car for a spirited drive on 90/94 and the boost is totally back!! It seemed like I could hear the turbo spinning up, or boosting...but I don't have a blow-off valve. I checked all the hose connections when I got home and everything seemed fine...so no idea on that. Changing the oil to 10w40 dino on Monday just to see if that helps things. I would REALLY REALLY like to get to Stage 0, so that I can get to Stage 1, and then 2!

The engine still sounds like it's chugging, but it seems to be coming from the rear, back of the block, down by the turbo or the headers...what could that be? Also the vibration seems to be coming from the rear bottom as well, so the rear hydraulic mount is definitely on the agenda. I'm still pulling P1310 and P0301. Still misfiring on #1. Urgh. What now???

Post by **erikv11** » 04 Oct 2013, 22:39

From BKM's early post, these are great suggestions to help troubleshoot the #1 misfire:

- Do you have spark to the #1 plug? Pull the plug wires one at a time and see if the idle changes
- Do a compression check (do all 5 cylinders, much more informative than just doing #1)
- Change to a new set of Bosch copper plugs (should be like $2 each at Pep Boys).

For the vibration: hydraulic mount problems are very rare, you will first want to check the "front engine mount" i.e. the one underneath the crank pulley, accessible via the passenger front wheel well. Get the front end up in the air and pull the tire.

Post by **erikv11** » 04 Oct 2013, 23:16

Another thing to try: (carefully) swap the #1 and #2 injectors. If the misfire follows the injector, you've found a problem. I don't expect it will but hey, easy enough to try and then you can rule out the fuel injection system.

taupehat · Post by **taupehat** » 04 Oct 2013, 23:20

Speaking as someone who just replaced a failed injector, ericv11's suggestion is really worthwhile. Swap will take about fifteen minutes if you don't drop a screw into the injector port on the manifold like I did... and if it is the injector they're easy to come by.

futureboycolin · Post by **futureboycolin** » 05 Oct 2013, 01:00

I did pull the wires on each cylinder individually while the car was idling, and the idle didn't change at all.

I have already replaced the lower right engine mount, and the upper torque bushing and firewall bushing.

I'm gonna try swapping the injectors, fingers crossed that that's the problem. Plus it will give me an excuse to go ahead and buy bigger injectors.

Post by **Ben850** » 05 Oct 2013, 07:14

I saw it mentioned earlier. Have you replaced O2 sensors? The '96 turbo wagon I had bought would not even stay running. That was the reason I got it for $650.00.
I had swapped everything from the MAF, cam position sensor, TPS, TCV, and fuel rail with regulator. I finally found a '95 turbo at the pick and pull that had what appeared to be nearly new, Bosch O2 sensors.
It was grasping at straws at this point, but after swapping them out, I waited for the complete loop cycle, approximately 2 minutes where it would sputter and stall. It didn't. It went to a perfect idle.

If you can get some known good O2 sensors (Bosch only) to swap out, or buy new ones if it is within your budget, I would try that.

Post by **rspi** » 05 Oct 2013, 07:59

I'm really shocked as to what I have read in this thread. If the car is shaking at low rpm's it is likely missing. If it's missing, the troubleshooting is simple.

Check the spark plug. Clean and regap it. If it's still missing, make sure it's getting fuel. If the plug is wet or you smell unburnt fuel out the exhaust, it has fuel to the piston. You can also pull the plug and hit the starter. If fuel is pumped out of the spark plug hole, it has fuel.

Checking for spark takes about 5 minutes.

Really, within an HOUR you should be checking compression, which takes 10 minutes.

Went through this process on a Saturn yesterday. Within 1 hour at the car found #2 at 10 psi. No need to purchase a spark plug, pull on vacuum lines (which do NOT cause misfires), run seafoam or change the oil.

Also not sure how a spirited run would help a misfire either. The next post should have compression numbers in it.

Post by **erikv11** » 05 Oct 2013, 09:21

futureboycolin wrote:I did pull the wires on each cylinder individually while the car was idling, and the idle didn't change at all....

This is impossible. I'd do it again, but pay more attention to the idle. Rev it is you have to.

On a normal running car, if every cylinder is firing, then each wire will cause the idle to become a little rougher as it is pulled. Because that cylinder stops firing. What you are looking for here, is whether or not the idle also drops/roughens as you pull the #1 wire. That will tell you if it is firing.

What everybody is telling you with the posts about spark plugs and compression is, you have to figure out if #1 is firing.

futureboycolin · Post by **futureboycolin** » 05 Oct 2013, 10:29

@rspi I was hoping that with seafoam, and a hard drive with revs over 4000 rpm that if the problem with cylinder #1 was carbon buildup on piston or valves, that perhaps it would be burned off.

I've been putting off doing a compression test because I don't want to face the possibility of the hard truth that it may be burnt valves, worn rings or worse.

What was your approach to remedy the problem once you found low compression?

taupehat · Post by **taupehat** » 05 Oct 2013, 11:12

Not speaking for rspi here, but when I was having trouble, a compression test was one of the first things I did. That was to inform me as to whether the engine was worth taking the trouble of further diagnosis - if one cylinder was truly "dead" then I'd have to make a hard decision about whether to rebuild the valves (or worse if it's the rings) or cut my losses on the car.

Think of it this way: imagine you spend eight hours and $200 in parts trying to fix around the edges, only to discover you have ground-up rings and massive scoring in the cylinder. Wouldn't you have rather skipped the earlier effort?

quick edit: If compression is low on one cylinder, pour a tablespoon of clean oil into that cylinder and re-test. If compression is still low, then the problem is valves. If compression tightens up, the problem is with the rings. Helps decide what to do next.