1992 RHD FD3S
MODS - HKS v Mount, PFC, HKS intakes, Aftermarket exhaust, Stock cat

Hello again, I was driving my car came to a stop and it went from idling and running perfect to buckling and running extremely poorly to the point I thought it was going to flood and stall out.
I noticed there was an audible turbo spool at low rom when driving and it was intermittent while at the same RPM, don’t know what this means, but it had never happened before

When I got home I noticed the cat was pluming smoke everywhere. I figured maybe the cat was clogged and the reason for my issue. Took it off and started the car and no change.

I thought maybe it was related to the secondary air injection and something with the air pump so I ripped out the ACV and I am going to install block off plates. o2 sensor is disabled because of pervious air pump issues.

Checked map sensor and vacuum lines and nothing was disconnected, checked PFC screen that shows voltages and solenoids and nothing was highlighted.

Idle vacuum is positive ~.01cmkg2

I don’t have access to a compression tester but listening to the crank with EGI fuse pulled it’s the same audible compression with no changes.


Any help is appreciated. Thank you

Jason

 

Where are you reading the idle vacuum? That reading is not possible at idle. There will ALWAYS be some vacuum with the throttle plates almost closed at idle. Something is wrong with the map sensor, its plumbing, or its wiring if you're reading it from that.

If the MAP sensor is telling the ECU there is zero vacuum, the fuel mixture will be WAY too rich with vacuum, i.e., very light or closed throttle.

 

I’m reading vacuum through the pfc. I will test the MAP sensor to see how it responds to artificial vacuum.

 

anyone have some advice?

 

What color is the smoke? If a coolant passage eroded and broke opening a path to the combustion chamber you would get similar symptoms. Any coolant boiling? Does the smoke smell sweet like coolant?

Did you also follow the vacuum from the Map sensor to the manifold. Sometimes they pop off on the manifold and if the hose is hard, it may feel like its connected still. As was stated, its almost impossible to be able to idle with those vacuum readings so it could very well be an issue with the MAP sensor or the wiring/vacuum associated with it. How did your test with the vacuum applied go with it?

Unfortunately this sounds like it could be a possible catastrophic failure. You may want to grab a compression tester to get a real compression reading. Bite the bullet and get a rotary compression tester or get a cheap one from autozone and pull the shrader valve out so you can see the pulses and get somewhat of an idea.

This could also be a stuck open injector but wouldn't explain the low idle readings.

 

Doesn't sound to me like a catastrophic failure with even cranking speed. I'm still betting on a MAP sensor issue.

 

Post a picture of the sensors/voltages screen on the PFC so we can see if anything is off there.

 

If I were a betting man, I'd also say MAP sensor issue. There are specs to test it in the FSM. Also, there should be a little filter on the MAP vac reference line. Make sure that's not clogged as well. Sounds to me like its running the way mine did when I plugged the vac reference into the wrong port on the UIM (it wasn't a vacuum port at all, so the MAP was always reading atmosphere) causing very similar issues.

 

That's what it sounds like to me as well but he said in his last post he would test the MAP sensor operation prior to this latest bump and why I asked what his results were.

This just brought back memories of a Friend who lost a corner seal with two others being cracked and had similar symptoms, cat caught on fire by the time he pulled into the shop because of all the unburnt fuel. Still had some compression but wasn't great.

 

Update, I tested my map sensor and it was reading the same as a known good one. The smoking cat was from a leaky rear transmission seal after further inspection, so that is unrelated to my engine issue.

The color of the smoke is black, not blue or white and I had started it after letting it sit for a day and it was the same so I’m ruling out coolant seal.

Car has been in pieces because of having to take out the ACV and all the other air pump related things.

Have not gotten to start it in a little bit because of that.

 

gotta hope it’s not this, I the engine was rebuild less than 5000 miles ago and I really try to take care of the car.

 

Looking through my PFC settings on PIM voltage, it was highlighted on option 1 and not on normal. I must have hovered over it and backed out not knowing that will enable that setting. I’ll start the car up and let you guys know what happens.