Gentlemqn Glen

I took my 2001 Safari to a smog check station. It failed. It did pass the visual inspection, but had a DTC P0300 code, and the oxygen sensor heater was not ready. So, I took the vehicle home and hooked it up to my scan tool and it showed the same P0300 code, plus two more (P0172 and P0175). At this point, I decided to do a tune up because I did not know how long it has been since the last tune-up.

This is what I did as a part of the tune up:

Installed (6) new Autolite Double Platinum APP605 Spark plugs (gapped at .060” )
Installed (1) new Duralast Distributor cap
Installed (1) new Duralast DR2030 Rotor
Installed (1 set) new Duralast Spark Plug Wires
Installed (1) new STP SA7421 Air Cleaner Element
Installed (1) new Duralast C1098 Ignition Coil
Installed (1) new Champion T5-650CH Battery
Installed (1) new Duralast SU109 Coolant Temp. Sensor
Installed (1) new Mass Air Flow Sensor
Installed (1) new Radiator (because the one that was in it had a crack)
Installed (1) new Fuel Pressure Regulator

After all of the above, the vehicle seemed to run much better. I put it back on the scan tool and it now it showed DTC P0171 and P0174, different codes. These codes were describing Fuel Trim System Lean on Banks 1 and 2. I will also mention that the vacuum gauge showed 21 inches of mercury, a steady needle, idling at 887 rpm. Fuel Pressure gauge showed 61 psi, and was holding pressure for at least 5 minutes after engine was shut off.

I did a drive cycle of at least 10 miles, and checked the I/M Readiness on the scan tool and it showed the catalyst, evap system and oxygen sensor heater were incomplete (INC).

I have checked the oxygen sensor by spraying carburetor cleaner into a vacuum line, monitoring the reaction of the sensor; It went from .8 millivolts to .9 volts when sprayed. Which is exactly what it should read according to the service manuals I am using. (The one that start with an “H” and the other one that starts with a “C”).

Once the lean condition DTC’s (P0171 & P0174 showed up) I replaced the intake manifold gaskets, thinking that would take care of the lean condition. Once the gaskets were replaced, the lean codes disappeared on the scan tool and I got a P0200 DTC.
Which indicates an Injector Circuit Problem. The vehicle was now very hard to start and has a significant lack of power. It won’t idle and the engine vacuum is low and the needle fluctuation is severe. I have never experienced this at any time with this vehicle.

I thought maybe the ignition timing was off. Prior to changing the intake manifold gaskets, the timing advance read 33 degrees and steady. Now it is hard to get a good reading from the scan tool because it is fluctuating between 8.5 degrees and 22 degrees at 1000 -2000 rpm. I tried to advance the distributor 1 tooth on the gear drive and the vehicle wouldn’t start. I am a Harley Davidson Master Mechanic with many decades of experience, but I’m not experienced with emission related problems on automobiles.
I feel like I am chasing my tail around and spending a lot of time and money. It seems like I am eliminating codes and making new codes show up. I need to get this problem resolved because my vehicle has expired tags now because of these problems. I would really appreciate any help or suggestions anyone can give to me. Thank you in advance.

StanVan

Is there any change of vacuum since the intake gasket change?

Gentlemqn Glen

Yes, it used to be 21a and steady. Now it's between 8.5 and 22 and very erratic with severe power loss. The vehicle won't even idle, but it used to idle fine.

StanVan

I'm somewhat confused. In your first post, you listed those values as timing advance.

But my guess is that you might have made a mistake when changing those intake manifold gaskets. As you probably know, that's where vacuum for the entire vehicle is produced. So, if you had steady vacuum before the gasket change, and unsteady vacuum after, that's where I'd start. The other thing that comes to mind is the vacuum reservoir. I forget what the symptoms were at the time, but on my '00 Astro(4.3), one of the nipples broke off from age. I'm at a point in my life where there's only so much I will do myself, and I paid someone to fix this one. But I'm told it's somewhere up under a fender(?)

kevinkpk

887 rpm , 21" hg, seems a little low at that rpm, what size engine?

Gentlemqn Glen

It has a 4.3 engine.. Thanks for responding. I am at a complete loss as to what's going on with this vehicle. It won't start, it cranks, but it won't start.

Gentlemqn Glen

Thanks StanVan for your information and suggestions. I appreciate it.