Ti swapped with S50

[CameraCourage]

Hey all, I have a 1995 Ti that had a cracked head so I pulled the motor sourced an S50 from a junkyard car that looked to be in great shape. I have gotten it all installed and it has an idle issue that I haven't been able to sort out yet.
It has two primary issues right now

• #1. Over charging battery

• #2. Idle bounces from about 500rpm to about 1100 rpm repeatedly.

It currently has no codes and no CEL. CEL does work, if I pull a sensor plug it will show the code for that sensor.
Here is the short list of things I have tried so far.

• -Checked vacuum lines- lines are plugged in, lines are in good shape.

• -Replaced ICV- Seemed like it was the most likely culprit at first, so I replaced it... no change.

• -Pulled and inspected all baffles in the intake elbow to make sure there wasn't any additional air coming in somewhere.

• -Installed a borrowed a Maf from a working car to test, no change

• -Pulled plugs and inspected

• -Checked Coils

• -Checked grounds

• -Checked starter wiring

• -Checked and confirmed all sensor plugs to make sure they are plugged in correctly and in good shape.

• -pulled and tested the VANOS solenoid

• -Swapped 1 RED 413 for another to test DME

Next on the list is to replace

• -Cam Position sensor

• -Throttle Position Sensor

[LIST]
The car runs pretty good when it is above idle, but it will just barely run at idle and stalls periodically as well. If anyone has any similar experiences and has some ideas I would love to hear, I'm running out of solutions...

[Bobtail_Bimmer]

Other things you can check are pcv valve and o2 sensors. They can mess with your idle as well. Im sure others will post with ideas. Good luck & hope u get it sorted out.

[Bluebimma]

Make sure you've routed your hoses properly for the charcoal canister and evap pieces. The vacuum lines under the throttle body should be checked to see if theyre routed to the correct two ports and not plugged. spray soething around the intake to head gaskets to make sure they haven't dried out. Make sure the FPR vac is plugged in.

[CameraCourage]

First off, thanks for the quick responses, I definitely appreciate it. I have been dragging my heals on this project and need to get it running!
I believe the vac hoses are routed correctly. I did pull each hose and inspected it, blew compressed air through them and checked their condition. I will go through those again just in case and verify their routing.

I forgot to mention that the O2 sensor is new and clearly works since it goes rich when I unplug it.

On this car I did route all the evap lines, everything coming into the charcoal canister is setup correctly, but I haven't found the little breather pipe that is supposed to come out of the canister. We did another car that we removed the charcoal canister all together, it was a full race car, and that car has no issues with the missing bits however.

When I had the intake manifold off I did replace all of the red gaskets that seal between the intake manifold and the engine. I have not inspected the connection at the throttle body however and I haven't done anything yet to spray anything to inspect for vacuum leaks. That is on the short list of things to do.

Also on the list of things to do, use a known good cam position sensor to test that. Also, use a known good TPS to test that. I haven't come across a PCV valve on this car, I'll pull out the book and look into that.

[Bluebimma]

It's right on the front. It's what connects the valve cover to the icv/intake manifold. It also bridges from the intake manifold to the Pcv

[CameraCourage]

Originally Posted by Bluebimma

It's right on the front. It's what connects the valve cover to the icv/intake manifold. It also bridges from the intake manifold to the Pcv

Oh, ok. I suppose I didn't really pay attention to what that was doing. I did check the o-ring on that, but I haven't inspected the valve function itself. I do know all the hoses are plugged into that properly however. I will grab a known working one of those as well and swap it as well.

[Bluebimma]

There's no valve. Just vacuum to the two ports

[CameraCourage]

Ok, if that is the case then I believe that is set up correctly.

[CameraCourage]

Originally Posted by CameraCourage

Ok, if that is the case then I believe that is set up correctly.

Is there any reason to inspect or replace the o-ring on the PCV? It is a bit worn, but otherwise it is complete

[Bluebimma]

It can create a vac leak

[CameraCourage]

Originally Posted by Bluebimma

It can create a vac leak

That is what I thought, I have seen a ton of them that seem like they very loose in the motor though so I didn't know if that was a problem or not.

[Bluebimma]

Yea, its a tight fit and supposed to snap into place. the small line goes under the intake to the hose that connects to the icv, if its not plugged in and the hose underneath isn't sealed, it can cause issues too. Can you get it to set a code when you unplug the gas cap? does it run differently? Usually theres vacuum if its been run and then the cap removed, sitting without it plugged causes engine to rev up and down 500rpm and will only even out once the cap is replaced and sets a 1221 code if im not mistaken. Its the same issue if you fill the tank while running, itll rev up and down and set a code and leave the light off.


Just blabbing off the top of my head the issues ive run into over the past five years. Hows the coolant temp sensor? Does the engine act differently with the DME coolant sensor unplugged or swapped with the cluster coolant sensor?

[CameraCourage]

Honestly that isn't a bad thought. I know one of the other guys at the shop siphoned a few gallons out of the car to get our Class 11 bug to the gas station a while ago, I wonder if he put the cap back on. I haven't gotten any codes though.

[CameraCourage]

Ok, I was able to make a few minutes this morning to go swap out a Cam Position sensor with a known good sensor... No change, I checked the gas cap too and it is tight. I wasn't able to get my hands on a TPS. I grabbed a Fuel Pressure guage on the way today also, but Apparently the S50 doesn't have a test port so i need to go pick up a t fitting.

I didn't do anything with the Coolant temp sensors today, I haven't heard that one, what should I expect when I pull that?

[CameraCourage]

I was down this weekend, Checked the Coolant sensors and they are all wired correctly, Started going down the road of checking the harness and we have found a few quirks. I am starting to suspect a short in the harness itself.