horrible mpg and weird idle drop

[Gerbil21]

well i didnt get to get gas and do a mpg check but i did go back down to 9.3 mpg. i will see if this weekend i will do compression, and vacuum test

 

[gmcman]

Did you check that vacuum port? If it's missing the cap and drawing vacuum it will cause a myriad of issues.

 

[Gerbil21]

Did you check that vacuum port? If it's missing the cap and drawing vacuum it will cause a myriad of issues.

I will check tonight but I would only imagine that would sound like a giant vacuum leak, right?

 

[Gerbil21]

OK I checked and the cap is there

 

[PProph]

The downstream sensor when good and hot should be ideally around .500, and steady...give or take but .800 is high......means it's a rich reading and could be from fuel or possibly the hydrocarbons related to the blue smoke from the breather.

Can anyone else confirm this? I've seen other members post that .700 to .800 steady is normal for downstream o2.

 

[KNBlazer]

200 miles on overhauled engine, these are the numbers I got....

 

[Gerbil21]

OK well I'm at 8.8mpg now but I haven't driven it anywhere yet just idling and reading values on live data. Stft seems off and I think cat may be going.

Also I got a few questions,
how much vacuum is felt at the pcv port on the resonator I can't feel any with my finger.

If you hold your finger over the pcv hose dose pressure build up after a few seconds?

Idk how bad my blow by is, if I even have much but I can see a bit of light blue smoke coming from the pcv hose and if I block it off there is a hiss sound when I let go, but if I take out the dipstick there is only a light hiss and a brief burst of smoke from the dipstick tube then a constant light smoke like the pcv, it is the same with the oil filler but much less which I'm sure is just because of the size of the oil filler as compared to the dipstick tube. But if I hold the pcv tube closed again with the dipstick closed as well I can see the smoke more but still not much.

The oil smells a bit of gas but not much and there is no gas smell in the exhaust even thought the pipe shakes and has the exhaust sound to go with it so that may be another sign pointing towards the cats but idk

Also that weird idle drop dose it get eliminated by the tune?

And one other thing is what Signs show up from a bad water pump I'm asking since the fan wiggles a bit

 

[Gerbil21]

Also what sounds are normal I have a constant ticking from fuel injectors

 

[Gerbil21]

Engine start

Ign. On engine off


Calibration id

 

[Gerbil21]

I haven't got the vacuum gauge yet but I see 5.5psi idling (11.2") @1.42v and 14.7psi (30") @4.84v engine off

And baro is 13.25 psi (26.9") @4.84v at idle and engine off

 

[Gerbil21]

I think my car might of been hit by lightning [emoji45]

I pulled these history and intermittent codes yesterday the only two I had was low coolant temp because of the 160* t stat that was there and cam solenoid but I cleaned it and all is fine also tb was cleaned twice

Threse codes have been there since i got the car even after taking off battery for a day twice there still here I used car gauge pro for this

Diagnostic Report
08/20/2014

-----------------------------------------------------------
Enhance Faults (4:51:33 PM)
History Codes
-----------------------------------------------------------

P0201 - Powertrain - Injector Circuit - Cylinder 1
P0202 - Powertrain - Injector Circuit - Cylinder 2
P0203 - Powertrain - Injector Circuit - Cylinder 3
P0204 - Powertrain - Injector Circuit - Cylinder 4
P1137 - Powertrain - HO2S Bank1 Sens2 Lean Sys or Lo Volts
P1138 - Powertrain - HO2S Bank1 Sens2 Rich or Hi Volts
P0495 - Powertrain - Fan Speed High
P0106 - Powertrain - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
P0108 - Powertrain - Manifold Absolute Pressure/Barometric Pressure Circuit High Input
P0462 - Powertrain - Fuel Level Sensor Circuit Low Input
P0112 - Powertrain - Intake Air Temperature Circuit Low Input
P0113 - Powertrain - Intake Air Temperature Circuit High Input
P1574 - Powertrain - EBTCM Sys-Stop Lamp Switch Circ Hi Volts
P0125 - Powertrain - Insufficient Coolant Temperature for Closed Loop Fuel Control
P0131 - Powertrain - O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
P0132 - Powertrain - O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
P0133 - Powertrain - O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0134 - Powertrain - O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P1133 - Powertrain - HO2S Insufficient Switching Bank1 Sens1
P0137 - Powertrain - O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
P0138 - Powertrain - O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
P0140 - Powertrain - No Description Available
P0141 - Powertrain - O2 Sensor Heater Circuit (Bank 1 Sensor 2)
P0171 - Powertrain - System too Lean (Bank 1)
P0172 - Powertrain - System too Rich (Bank 1)
P1171 - Powertrain - Fuel Sys Lean during Acceleration
P0894 - Powertrain - Transmission Comp. Slipping
P2a01 - Powertrain - No Description Available
P0300 - Powertrain - Random/Multiple Cylinder Misfire Detected
P1380 - Powertrain - Misfire Detected-Rough Road Data Not Available
P1381 - Powertrain - Misfire Detected-No Comm with Brake Ctrl Mod
P0420 - Powertrain - Catalyst System Efficiency Below Threshold (Bank 1)
P0455 - Powertrain - Evaporative Emission Control System Leak Detected (gross leak)
P0410 - Powertrain - Secondary Air Injection System
P0496 - Powertrain - EVAP Emission High Purge Flow Fault
P0442 - Powertrain - Evaporative Emission Control System Leak Detected (small leak)
P0446 - Powertrain - Evaporative Emission Control System Vent Control Circuit
P0461 - Powertrain - Fuel Level Sensor Circuit Range/Performance
P0502 - Powertrain - Vehicle Speed Sensor Circuit Low Input
P0503 - Powertrain - Vehicle Speed Sensor Intermittent/Erratic/High
P0506 - Powertrain - Idle Control System RPM Lower Than Expected
P0507 - Powertrain - Idle Control System RPM Higher Than Expected
P0530 - Powertrain - A/C Refrigerant Pressure Sensor Circuit
P0562 - Powertrain - System Voltage Low
P0563 - Powertrain - System Voltage High
P0463 - Powertrain - Fuel Level Sensor Circuit High Input
P0130 - Powertrain - O2 Sensor Circuit (Bank 1 Sensor 1)
P0128 - Powertrain - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
P0705 - Powertrain - Transmission Range Sensor Circuit Malfunction (PRNDL Input)
P0711 - Powertrain - Transmission Fluid Temperature Sensor Circuit Range/Performance

-----------------------------------------------------------
Enhance Faults (4:52:31 PM)
Intermittent Codes
-----------------------------------------------------------

U1301 - Network - No Description Available
P0201 - Powertrain - Injector Circuit - Cylinder 1
P0202 - Powertrain - Injector Circuit - Cylinder 2
P0203 - Powertrain - Injector Circuit - Cylinder 3
P0204 - Powertrain - Injector Circuit - Cylinder 4
P1137 - Powertrain - HO2S Bank1 Sens2 Lean Sys or Lo Volts
P1138 - Powertrain - HO2S Bank1 Sens2 Rich or Hi Volts
P0495 - Powertrain - Fan Speed High
U1041 - Network - No Description Available
U1064 - Network - No Description Available
P0106 - Powertrain - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
P0107 - Powertrain - Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
P0108 - Powertrain - Manifold Absolute Pressure/Barometric Pressure Circuit High Input
P0462 - Powertrain - Fuel Level Sensor Circuit Low Input
P0112 - Powertrain - Intake Air Temperature Circuit Low Input
P0113 - Powertrain - Intake Air Temperature Circuit High Input
P0117 - Powertrain - Engine Coolant Temperature Circuit Low Input
P0118 - Powertrain - Engine Coolant Temperature Circuit High Input
P1574 - Powertrain - EBTCM Sys-Stop Lamp Switch Circ Hi Volts
P0122 - Powertrain - Throttle/Pedal Position Sensor/Switch A Circuit Low Input
P0123 - Powertrain - Throttle/Pedal Position Sensor/Switch A Circuit High Input
P0125 - Powertrain - Insufficient Coolant Temperature for Closed Loop Fuel Control
P0131 - Powertrain - O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
P0132 - Powertrain - O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
P0133 - Powertrain - O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
P0134 - Powertrain - O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
P1133 - Powertrain - HO2S Insufficient Switching Bank1 Sens1
P0137 - Powertrain - O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
P0138 - Powertrain - O2 Sensor Circuit High Voltage (Bank 1 Sensor 2)
P0140 - Powertrain - No Description Available
P0141 - Powertrain - O2 Sensor Heater Circuit (Bank 1 Sensor 2)
P0171 - Powertrain - System too Lean (Bank 1)
P0172 - Powertrain - System too Rich (Bank 1)
P1171 - Powertrain - Fuel Sys Lean during Acceleration
P0894 - Powertrain - Transmission Comp. Slipping
P2a01 - Powertrain - No Description Available
P0218 - Powertrain - Transmission Fluid Over Temperature Condition
P0300 - Powertrain - Random/Multiple Cylinder Misfire Detected
P0336 - Powertrain - Crankshaft Position Sensor A Circuit Range/Performance=
P0341 - Powertrain - Camshaft Position Sensor A Circuit Range/Performance (Bank 1 or Single Sensor)
P0340 - Powertrain - Camshaft Position Sensor A Circuit (Bank 1 or Single Sensor)
P0315 - Powertrain - Crankshaft Position System Variation Not Learned
P1380 - Powertrain - Misfire Detected-Rough Road Data Not Available
P1381 - Powertrain - Misfire Detected-No Comm with Brake Ctrl Mod
P0420 - Powertrain - Catalyst System Efficiency Below Threshold (Bank 1)
P0455 - Powertrain - Evaporative Emission Control System Leak Detected (gross leak)
P0410 - Powertrain - Secondary Air Injection System
P0496 - Powertrain - EVAP Emission High Purge Flow Fault
P0442 - Powertrain - Evaporative Emission Control System Leak Detected (small leak)
P0446 - Powertrain - Evaporative Emission Control System Vent Control Circuit

 

[DAlastDON]

I think my car might of been hit by lightning [emoji45]

Or you have a gremlin infestation.

 

[Gerbil21]

Does anyone still run vin checks to see what work was done or if my pcm was ever updated

 

[KNBlazer]

Does anyone still run vin checks to see what work was done or if my pcm was ever updated

With my truck, I used my live data feature on my scanner and then went to

https://tis2web.service.gm.com/tis2web

I compared my Cal ID's and found out I'm 2 updates behind...

 

[Gerbil21]

With my truck, I used my live data feature on my scanner and then went to

https://tis2web.service.gm.com/tis2web

I compared my Cal ID's and found out I'm 2 updates behind...

You can check above I posted some live data and the cal. Id also I have checked that site before and don't remember seeing anything but I'm going to check again now thanks

Edit:Well its amazing when you know what your actually looking for lol turns out I am two updates away the next updates are for hard start, black smoke and the other is for cat. Conv. Monitoring at idle

 

[Gerbil21]

Do you know If someone is still Running the Vin checks that show work done?

 

[KNBlazer]

Do you know If someone is still Running the Vin checks that show work done?

I don't know... I would assume yes...

 

[Gerbil21]

I don't know... I would assume yes...

Most threads I saw said currently unavailable
Do you know how much a update will be for the PCM?

 

[KNBlazer]

Most threads I saw said currently unavailable
Do you know how much a update will be for the PCM?

You can call any GM dealer, preferably GMC or Chevrolet... I called my local dealers and all but 1 quoted me $100 ... the one that didn't, quoted me $55....

 

[Gerbil21]

You can call any GM dealer, preferably GMC or Chevrolet... I called my local dealers and all but 1 quoted me $100 ... the one that didn't, quoted me $55....

I had actually just called one next to me and they said about that same price, do you think it would be better to get a tune?

 

[KNBlazer]

I had actually just called one next to me and they said about that same price, do you think it would be better to get a tune?

The general consensus here on GMTNATION would be yes... personally, I can't advice either way since I'm stock... Just about everyone who reply back are happy with their tunes....

 

[Blckshdw]

I had actually just called one next to me and they said about that same price, do you think it would be better to get a tune?

The general consensus here on GMTNATION would be yes... personally, I can't advice either way since I'm stock... Just about everyone who reply back are happy with their tunes....

I think the big thing is the removal, or reduction, of torque management. The first time I drove my truck after getting tuned, I had the proverbial "Why the hell didn't I do this sooner?" moment. Basically your truck will feel more alive, and much more responsive when you push the skinny pedal. Some have reported MPG improvements, but for me, they stayed the same, even when trying a 93 octane tune for about 7 months.

 

[Gerbil21]

Well if anything improves my mpg now at 8.7 it would be a good selling point for them

 

[Blckshdw]

True, hopefully it's that simple, cuz you should be getting almost twice what you're getting now. With the LWB, slightly oversized tires, and a lead foot I'm not afraid to use, I average 15-16 MPG per tank, depending on how much highway time is mixed in with the daily commutes.

 

[Gerbil21]

True, hopefully it's that simple, cuz you should be getting almost twice what you're getting now. With the LWB, slightly oversized tires, and a lead foot I'm not afraid to use, I average 15-16 MPG per tank, depending on how much highway time is mixed in with the daily commutes.

Yea I wish I had that and I really want to figure out what the problem is I just hope it's an easy one and done fix. My brothers 99 grand Cherokee with the 4.0 i6 gets 12mpg with 138k and previous owner neglect and my last car a crown Vic police interceptor that weighted as much as our swb trucks but with a 4.6 v8 and was always driven hard was better on gas than this and it had ALOT of problems

 

[KNBlazer]

Yea I wish I had that and I really want to figure out what the problem is I just hope it's an easy one and done fix. My brothers 99 grand Cherokee with the 4.0 i6 gets 12mpg with 138k and previous owner neglect and my last car a crown Vic police interceptor that weighted as much as our swb trucks but with a 4.6 v8 and was always driven hard was better on gas than this and it had ALOT of problems

With all of those codes, I would think you need a new PCM...

 

[Gerbil21]

With all of those codes, I would think you need a new PCM...

But they are only intermittent and history codes even Thought they seem to be hard written since I have pulled power from the PCM twice for a whole day and there still there.

I got no codes for current, pending, or manufacturer

If I get a tune or a dealer reprogramming can they wipe mines clean or do I just need a new pcm

 

[Gerbil21]

Ok well my mpg on the dic went up to 8.8mpg yay... [emoji45]

But I finally got to count the real numbers and I actually get after driving 34.5 miles and using 1/2 to 1/4...

6.9MPG[emoji33] [emoji33] [emoji33] [emoji27] [emoji24]

So yea something is definitely wrong
Unless my fuel gauge is off and I only used 4 gallons then I get 8.6mpg which means my dic is slightly optimistic [emoji38]

Please every trailvoy wizard HELP!

I will be doing compression test this Sunday and will do spark test soon also I will see if u can rent a vacuum gauge as well

P.s. I am not referring to the os at all the only wizards the have are ads to a mmo[emoji3]

 

[Gerbil21]

Ok I did another count and used the fuel used counter from the dic and I used 4.5 gallons with 37.7 miles driven so its just above 1/4 tank and with that I'm getting 8.37mpg

How long does it take for the rear o2 to steady out and what is a normal ltft & stft with cold starts up to op. Temp also anyone know what fuel/air mixture should be on a cold start mines went from 11:1 to 14.6:1 at op.temp

 

[IllogicTC]

How long does it take for the rear o2 to steady out and what is a normal ltft & stft with cold starts up to op. Temp also anyone know what fuel/air mixture should be on a cold start mines went from 11:1 to 14.6:1 at op.temp

LTFT and STFT shouldn't really roam on a cold start. The engine will run under "open loop" until the desired O2 operating temperature is reached on the upstream. What this means is it just takes the estimated amount of air going in, injects an equal (compared to the air) amount of fuel, and does no O2 checking to adjust. When the system goes CLOSED, then you'll get LTFT and STFT that actually matters.

Rear O2 should be steadied by the time the engine has reached normal operating temperature, I would assume. You can use an infrared thermometer to check out the catalytic converter - the front weld ring should be maybe 2-300 degrees, and the rear weld ring should be significantly warmer, 4-500 or so. An extremely hot cat (700+) is likely to have a meltdown. A cat that measures the same on both sides after a full warm-up and maybe a cruise around the block just to be sure has already burnt out.

A backpressure test may be what'll help you figure this out - my suspicion is that your catalytic converter may be partially clogged, at least. Does the engine seem to lack power at all?

 

[gmcman]

Since all these codes are based on milli volts or a 5V reference, have you checked all your grounds? Maybe the PCM is bad, maybe need a reflash, maybe the PCM is from another vehicle.

 

[Gerbil21]

The car runs great other than the typical 4l60e 1-2 shift, it wasn't truly cold outside but it was the first start of the day also closed loop came pretty quick but that may be because I had the key on and engine off and the o2 heater may of been running

Also the rear o2 was bouncy but once it got towards op. Temp it stood at .750-.800

 

[Gerbil21]

Since all these codes are based on milli volts or a 5V reference, have you checked all your grounds? Maybe the PCM is bad, maybe need a reflash, maybe the PCM is from another vehicle.

Is there any I.d. on the pcm that I can look for? Also grounds looked good since everything in the engine bay looks new and under the car is clean too but idk the true history of the car I only had it for about 3 months but I will check as many as I can see tomorrow. Are there any important ones?

 

[gmcman]

I wonder if the previous owner changed the PCM then sold it, only becasue it has a laundry list of stored codes. It takes awhile for the rear O2 sensor to stabilize but I think .800 is high. Someone else needs to chime in on this with the normal range,

If that were my vehicle given what you told me, I would first check vacuum and perform a compression test, and see if there are AC Delco O2 sensors installed.

 

[Gerbil21]

I wonder if the previous owner changed the PCM then sold it, only becasue it has a laundry list of stored codes. It takes awhile for the rear O2 sensor to stabilize but I think .800 is high. Someone else needs to chime in on this with the normal range,

If that were my vehicle given what you told me, I would first check vacuum and perform a compression test, and see if there are AC Delco O2 sensors installed.

A few post up knblazer got .790 IIRC so it seems good also no smells or sounds. Also yes the upstream is acdelco I replaced it recently as for the rear idk but its prob. original.

 

[Gerbil21]

I haven't got the vacuum gauge yet but I see 5.5psi idling (11.2") @1.42v and 14.7psi (30") @4.84v engine off And baro is 13.25 psi (26.9") @4.84v at idle and engine off

 

[gmcman]

I checked mine today and took a video of the entire warm up. A few times I was near .700 but under a constant load after it's good and hot it's closer to .500 to .600.

I'm not sure of the specs for the motor but I think ,800 is fairly rich or a failing cat....not 100%.

 

[Gerbil21]

I will check again what I get under load also would the cat kill mpg that bad? I had a crown Vic that killed a cat in a week most of the time it started and ran so rich I thought it was leaking fuel and it would stall from being flooded but as far as I can tell mpg were not as bad and it weights the same as our trucks

Also it would be nice if you can upload a vid of a few things such as fuel trims, o2 volts, map sensor, etc.

 

[PProph]

since just changing out my CAT my downstream steadies anywhere between .600-.800 according to torque. the real important thing to note on it is that it stays steady i think.

 

[KNBlazer]

since just changing out my CAT my downstream steadies anywhere between .600-.800 according to torque. the real important thing to note on it is that it stays steady i think.

My CAT is original, last night I hooked up my scanner, and my live data showed a constant .735 on downstream.... I'm going to check temps at the inlet and outlet...Waiting on delivery of IF Thermometer...

Did you use a GM CAT?