Tech Area > General Auto Tech
Failed upgrade to new 3"downpipe and resulting problems
kjhansen:
Shimy87, I appreciate your input.
To clarify matters a little: I owned a Turbo Buick for many years back in the 90s until 2009 and did almost all my own work. So I have an understanding of the basics--although Steve's Vortex articles are very good and I learn (or re-learn) from them still. However I don't claim to be an expert, but I'm also not new to the car or its problems.
However, that was many years ago. I am now 72 years old and have a very bad back. This makes it very hard for me to get down under a car. Pain is excruciating.
Second, controlling the boost. The whole point of replacing the downpipe was to make it so I COULD control the boost, as the wastegate on the old downpipe was NOT working. I DON'T WANT TO RUN 30PSI OF BOOST. And it is no longer doing that. However, it's not because I got the new downpipe on. I did not--or rather, my mechanic did not. It's got the old downpipe back on, but it's not running like it did before with the old downpipe on. It doesn't have the power it had before, and it's popping/backfiring at 18psi of boost and power is dropping off even more. I removed the boost line from the turbo to the wastegate controller so it would run 30psi of boost again, but it will not. Same symptoms.
Why? How can I fix this?
It could be an exhaust leak before the turbo, where the downpipe attaches. That would explain the loss of power. I've had that happen before on my old TR. It blew the gasket between the turbo and the headers. But it didn't pop/stutter or backfire. I don't know if my muffler guy ever removed the turbo from the headers though. I don't think he would have needed to. In any case, in the past that only caused a drop off in power. The engine still ran smoothly with no backfiring, etc.
Could it be an exhaust leak where the turbo and downpipe connect? This is supposed to be a metal-to-metal connection, no gasket or gasket goop required. The muffler guy did put high-temp exhaust gasket goop on it. You can see the orange stuff. Would that cause this kind of problem? Could it be messing with the O2 sensor?
Could it be something electrical? It feels like maybe, when the car is accelerating, and it backfires, that the engine is stalling and restarting very quickly and backfiring when it restarts. That appears to be between shifts. The transmission has a shift kit in it and shifts very firmly with a solid jerk. Just now I took the car for a drive around the block (that's 4 miles out here in the country) to see if it would run over 18psi of boost after I disconnected the boost line to the boost controller. It should have, since there was no pressure to open the wastegate. It didn't. Still backfired, popped and stuttered at about 18psi. Anyway, after I got back I opened the hood with the engine running to see if I could spot any physical problems, like soot around a turbo connection or broken wires. No such luck. So I closed the hood--firmly. The hood struts are pretty new and give a lot of resistance. When the hood closed, the engine stalled. Very interesting. Like there might be a loose electrical connection under the hood? Could the disconnected sparkplug wire have caused damage to the engine when I drove it home? It was only about 5 miles.
I was hoping someone on this board had experienced something like this.
kjhansen:
~JM~ New motor mounts and all new body bushings (even some missing ones) were installed just about 3 years ago. I definitely need a mechanic who knows these cars though. I'm just not up to it anymore.
xracerx13:
loose wire connection at the battery?
Steve Wood:
driving the car with one plug not firing does not do the cylinder any good because the raw gas can wash the oil film off the cylinder wall and eat the rings on the piston up. Hopefully five miles is not enough to do serious harm. Pull the dipstick out and smell it...if it does not smell strongly of gas, it may not be bad. If it does, about all you can do is change the oil.
Any time the O2 reads much above 800, then the car is way too rich and this abnormal combustion can set the knock sensor off. If it is showing high 800's now, you have to figure out why and get it back to normal range. Some times Eric's chips are a bit rich but not that much. I guess check the maf numbers and see if they are reading high, that can cause it. Maybe the O2 sensor is coated because it got to much raw fuel on it? That could do it also. You might trying starting car and seeing if holding in park at a higher rpm cleans it up...but I suspect pulling it out and replacing it, or at least cooking it with a propane torch if it looks blacked and coated.
I thought I saw some mention of high 800s but Now I don't see it...so the O2 may not be the problem.
What I would do is check the resistance of the coil pack that had the disconnected plug. Running these cars with disconnected plug wires can blow the coil pack or the module pretty fast.
Most silicones are sensor safe these days. the sensor is below the joint so it should not be a silicone problem.
Steve Wood:
Also make sure the spark plugs on question does not have a cracked insulatoe after being hit
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