1991 ZR1 ODB1 Port Location

[roadczar]

The plan for today is to replace the spark plugs and recheck for vacuum leaks...

Looked at couple of the plugs. The first looked OK, but the second looked pretty sooty. The spark looked strong. Injectors seem like a likely culprit.

[roadczar]

Forgot to mention - Last owner had a Doug Rippee Performance chip installed. I'm not familiar with that tuner. I wonder if it would be worthwhile to go back to the stock chip that came with the purchase....?

[XfireZ51]

Some of the sootiness may be due to the issues you described when you first got the car. I would get new plugs and take a look after a few drives. If you can do a scan, see where the BLMs are.

[roadczar]

Originally Posted by XfireZ51

Some of the sootiness may be due to the issues you described when you first got the car. I would get new plugs and take a look after a few drives. If you can do a scan, see where the BLMs are.

What does BLM stand for?

[XfireZ51]

Originally Posted by roadczar

What does BLM stand for?

Block Learn Multiplier. It is active in Closed Loop. At 128, it means the ECM is making no change to the base fuel map. So a scantool will tell you if you're running rich or lean and where.

[roadczar]

No luck after replacing the plugs
Did the paper clip diagnostic:
http://youtu.be/tl7aOi9GetY

From what I could tell:
31 - Cam Sensor Missing or Too Many Pulses
33 - MAP Sensor Voltage High
44 - Oxygen Sensor (Left Bank Lean)
55 - Fuel Monitor Lean
64 - Right Oxygen Sensor (Right Bank Lean)
66 - ??

Looks like a mess?

[XfireZ51]

Originally Posted by roadczar

No luck after replacing the plugs
Did the paper clip diagnostic:
http://youtu.be/tl7aOi9GetY

From what I could tell:
31 - Cam Sensor Missing or Too Many Pulses
33 - MAP Sensor Voltage High
44 - Oxygen Sensor (Left Bank Lean)
55 - Fuel Monitor Lean
64 - Right Oxygen Sensor (Right Bank Lean)
66 - ??

Looks like a mess?

When you have multiple MALF codes like this, first place to look is making sure the memcal is seated properly. Also, disconnect the BATT and erase. These may all be in history. Make sure to see if they come back, ie CEL again.
Also, make certain the ECM ground is in good shape. I hope you have an FSM.

[roadczar]

I did reseat the chip. Disconnected the battery, then went for a 50 mile drive. No codes, but still running like crap.

What is the part number of manual? I do have a ZR1 supplement.

Went for another drive and it threw 55. Fuel pressure?

[mike100]

I would say to ohm out the injector harness. There's a link to the how-to somewhere- It will take about an hour, but you can meter out the injector resistance to find the worst injectors. If you even have one bad one, plan on doing that for sure. It sounds like one other thing might be wrong as well.

One bad O2 sensor on one bank will also cause issues...it would save a ton of time if you can meet up with somebody with a laptop program or the factory tech1 scanner to look at operating parameters real-time when the engine is running- not just reading code history.

[XfireZ51]

Originally Posted by roadczar

I did reseat the chip. Disconnected the battery, then went for a 50 mile drive. No codes, but still running like crap.

What is the part number of manual? I do have a ZR1 supplement.

Went for another drive and it threw 55. Fuel pressure?

Fuel pump(s)?. At least the other codes didn't come back.