95 850 HORRIBLE knocking after tranny swap - not solved Topic is solved

850TurboTurtle · Post by **850TurboTurtle** » 08 Sep 2015, 18:38

Just started it up after swapping on a tranny from my donor car. The car is running very rough: it was hard to get started initially, then refused to idle, and if you give it a little gas it either surges to 3500rmp or dies. But the scary thing is this random knocking sound, like a bolt is rattling around somewhere inside the engine or tranny.

The sound comes at random intervals, but generally 2-5 seconds apart. It's a solid sound, but not sharp like a metallic clang. More of a wooden sound, almost like a backfire or a huge detonation 'knock'. Or pounding on the underside of the tranny with a metal mallet. Sometimes there appears to be a muffled 'puff' noise with it.

The sound appears to be coming from the right side of the turbocharger area, or below it, perhaps in the tranny axle area. In the linked videos it would be about under the turbo outflow pipe on the right. I had my ears right down there and could tell within a few inches the angle, though not how far down.

Here is the video on YouTube:

I was careful when reinstalling the tranny to have the torque converter fully installed with .55" clearance before attaching to the flex plate. (But doesn't it move closer to the flex plate when you tighten the bolts?) But I've heard that if you do it wrong the tranny will chew itself apart as soon as you start the car.

But I'm hoping that it's not the tranny, its something to do with timing or computer connections, since the car is running so roughly regardless of the tranny.

I'm desperate to get this car running so I can have a commuter car by the end of the week. All ideas deeply appreciated.

Post by **tryingbe** » 08 Sep 2015, 19:51

Did you take the flexplate off?

Post by **Ozark Lee** » 08 Sep 2015, 19:52

It doesn't sound like something loose, I think you are correct about it being detonation / backfire. Did you remove the ignition wires in the process? If so, double check that the order is correct (don't use Haynes as a guide since it is wrong). Robert has a video with the correct ignition wire sequence.

What codes are you posting in Port A-2? The codes may or may not be helpful but it is good information to have.

When you installed the torque converter did you feel it "clunk" when it seated into the front of the transmission? It is typically a pretty distinct feel when it bottoms out. Did you remove the flex plate to change the RMS? I think it only goes back on indexed correctly but I have only dealt with a flywheel as far as reinstalling one. If the flex plate is on incorrectly it messes up the crank position signal.

...Lee

Post by **dosbricks** » 08 Sep 2015, 20:45

Did you remove the knock sensors? I've read that they are persnickety about orientation. Are 1 and 2 plugged into their original sockets? Hopefully this is something external.

850TurboTurtle · Post by **850TurboTurtle** » 08 Sep 2015, 22:39

Thanks all for the feedback!

1. I did remove the plug wires from the plugs, but put them right back where they came from. Given wire length it's impossible to mess that up. I didn't undo the distributor cap end at all.

2. No codes yet. Maybe it has to run a bit longer to throw them?

3. I did feel the torque conv clunk in (in two steps) as I rotated it and pressed it in, then measured setback with a straight edge and ruler.

4. I did remove flex plate and changed RMS. Reinstalled with same, cleaned, and permatexed, bolts. There was an indexing post in the engine bolt plate and matching hole in the flex plate so it could only go on one way. Plus, I put score marks on both before removing to be sure and they were both aligned on reassembly.

5. I disconnected all the sensors from the wiring harness, but I don't remember removing anything from the engine itself. I don't know which are the knock sensors and where they sit on the engine, but I'll try to look that up.

Finally, I'm pretty sure the car ran out of gas just before I started the swap. (It sat for months, on empty, but I would start it from time to time to keep it lubed up.) The last time I started it it ran for a few minutes and died before I could park it in the garage. I figured it just ran dry.

So, I added a gallon when the job was done, and with the key on so fuel pump was running, pressed the fuel rail Schrader valve until it stopped sputtering and blowing bubbles. But, could it also be that it's still just too low and not getting fuel everywhere? Or still bubbles in the system? Though I'm not sure how that would explain the racing or clunking.

Just now I started it again to drive it 10' into the garage. It ran unevenly, and died the first few times as I put it in gear, so I gave it a little more gas. The engine surged past 3k RPM, in gear, even after I took my foot off the gas, for about two seconds. (Happily, the brakes kept me from going through the garage...) But, that was another really strange symptom. Hopefully one of these symptoms will help us zero in on the problem.

Also, it lost a lot of tranny fluid during the swap, of course, and I haven't topped it off because I'm not sure how much to add and don't want to overfill - but the dipstick was reading past the full line when it was sitting, cold. After the 1-2 minutes it has run, it now shows full/cold, which I'm pretty sure is a lie. But, could low fluid account for the clunking, if not the rough engine?

Azik09 · Post by **Azik09** » 09 Sep 2015, 02:23

Sounds exactly like backfiring caused by lean fuel mixture. Try to disconnect MAF sensor and start engine. If it will work better, attentively check all intake system and vacuum hoses for leaks.
Most probably that plastic hose between MAF and turbo inlet is not fitted and tighten correctly.

850TurboTurtle · Post by **850TurboTurtle** » 09 Sep 2015, 13:07

Thanks Azik09. I did disconnect the MAF but no change. Next I'll dig down and make sure all vac lines and sensors are connected. Any other ideas?

850TurboTurtle · Post by **850TurboTurtle** » 09 Sep 2015, 14:35

More info: it seems that I never hear the clunk sound when the engine is above 2k RPM. Only at lower RPM. Still rough under 2k. Haven't found anything disconnected yet. Still digging...

850TurboTurtle · Post by **850TurboTurtle** » 09 Sep 2015, 14:37

I did remove the injectors from the intake when I removed the manifold. Could this be caused by a damaged or loose injector, or something related?

Here's a video of the injectors spraying. Seems fine to my untrained eye. All five look the same.

Post by **abscate** » 10 Sep 2015, 01:02

This sounds a lot like my 1999 did with loose induction. The metering is completely screwed up at idle but kind of works at mid Rpm range ..followed by backfiring and WONK ! Detonation

Track all your induction hoses from turbo in , to do this right you have to remove each piece , inspect for splits , replace clamps. Use a flashlight to look for splits