engine codes and poor fuel economy (Page 4/4)
cartercarbaficionado MAY 29, 01:04 PM
still throwing a code at highway speeds but it clears it if I idle too long and won't flash it. I have a feeling it's egr based on some other symptoms and I would like to remove it and get a prom piggyback chip (holder?) to flash the ecm parameters for the egr delete
if anyone has any Good sites for the block off plates and chips let me know
cartercarbaficionado JUN 12, 10:47 PM
it set another code 22. also surging like a carb out of gas when held at one throttle position. more importantly I did figure how where the exhaust leak was. or rather it decided to make itself very known at 3 am last night with a hellacious backfire and some oil burning off the rear header as I guess it finally got pretty hot. got quite a few cuts and rust in my eyes and some interesting chunks of heat shield. hence the French sign language

[This message has been edited by cartercarbaficionado (edited 06-12-2024).]

Yellow-88 JUN 13, 11:16 PM
[/b]
quote
[B]Originally posted by cartercarbaficionado:

it set another code 22. also surging like a carb out of gas when held at one throttle position. more importantly I did figure how where the exhaust leak was. or rather it decided to make itself very known at 3 am last night with a hellacious backfire and some oil burning off the rear header as I guess it finally got pretty hot. got quite a few cuts and rust in my eyes and some interesting chunks of heat shield. hence the French sign language






Code 22 is TPS signal low. Below .25 volts. You said earlier that you read .35 volts at the TPS at closed throttle. The ECU doesn't see the throttle open until 1.25 volts.
So .... .35 to 1.25 is a tiny lag between what the ECM sees and what's really happening.

Because you read .35 at closed throttle, sudden, intermittent code 22 looks like a "scratchy" connection. I'm thinking that below .25 volts is a temporary open circuit.
Or .... a bad connection or .... far worse ..... a break in a wire somewhere buried deep in the bowels of the engine harness!!
Did that "back fire" occur when you attempted to open the throttle quickly from idol? Or what action caused that reaction? Fortunately, the laws of physics don't break.
Please don't tell me that weirdness did it ..... even if it did.
cartercarbaficionado JUN 13, 11:26 PM

quote
Originally posted by Yellow-88:

[b][/b]
Code 22 is TPS signal low. Below .25 volts. You said earlier that you read .35 volts at the TPS at closed throttle. The ECU doesn't see the throttle open until 1.25 volts.
So .... .35 to 1.25 is a tiny lag between what the ECM sees and what's really happening.

Because you read .35 at closed throttle, sudden, intermittent code 22 looks like a "scratchy" connection. I'm thinking that below .25 volts is a temporary open circuit.
Or .... a bad connection or .... far worse ..... a break in a wire somewhere buried deep in the bowels of the engine harness!!
Did that "back fire" occur when you attempted to open the throttle quickly from idol? Or what action caused that reaction? Fortunately, the laws of physics don't break.
Please don't tell me that weirdness did it ..... even if it did.


nope rapid decel. I drive this pretty aggressive with 4.5k rpm after my downshift and hard on the brakes so it's usually screaming and throwing huge fireballs
I did set the tps there but apparently 0.5 volt is fine so I'll probably set it there, also will check the harness once I get some new exhaust parts. could that low voltage cause the long cranking times and my still very bad fuel economy? because I'm fairly sure 15 mpg highway isn't quite right
Yellow-88 JUN 14, 11:25 AM

quote
Originally posted by cartercarbaficionado:

nope rapid decel. I drive this pretty aggressive with 4.5k rpm after my downshift and hard on the brakes so it's usually screaming and throwing huge fireballs
I did set the tps there but apparently 0.5 volt is fine so I'll probably set it there, also will check the harness once I get some new exhaust parts. could that low voltage cause the long cranking times and my still very bad fuel economy? because I'm fairly sure 15 mpg highway isn't quite right



Huge fireballs? When the Renault F1 first started using a turbo in the early 80s, the fire balls weren't even huge. Pretty cool but not huge.
Clearly there is unburnt fuel in the exhaust. Anybody want to jump in on Carters fireballs?

The TPS closed throttle setting can have only a tiny effect on the initial throttle response coming off closed throttle. Below .25 volts might confuse the ECM and cause some issue but I don't know what it would look like. No need to dig into the harness until you have verified that there is an actual problem there. You seem to like immediately digging deep into stuff but ...... that's just "chasing your tail".

Aggressive driving equals poor fuel economy. You can't get something for nothing.
cartercarbaficionado JUN 14, 06:36 PM

quote
Originally posted by Yellow-88:


Huge fireballs? When the Renault F1 first started using a turbo in the early 80s, the fire balls weren't even huge. Pretty cool but not huge.
Clearly there is unburnt fuel in the exhaust. Anybody want to jump in on Carters fireballs?

The TPS closed throttle setting can have only a tiny effect on the initial throttle response coming off closed throttle. Below .25 volts might confuse the ECM and cause some issue but I don't know what it would look like. No need to dig into the harness until you have verified that there is an actual problem there. You seem to like immediately digging deep into stuff but ...... that's just "chasing your tail".

Aggressive driving equals poor fuel economy. You can't get something for nothing.


true but the fuel economy isn't changing significantly (from 15 mph to 13 mpg) between driving like a grandma and driving with my foot welded to the floor at 110 mph.
also would probably dig into the harness to manage it better since it's a mess and looks terrible and has melted on the exhaust twice during my ownership despite it being continuously ziptied out of the way
Yellow-88 JUN 15, 10:57 AM

quote
Originally posted by cartercarbaficionado:

true but the fuel economy isn't changing significantly (from 15 mph to 13 mpg) between driving like a grandma and driving with my foot welded to the floor at 110 mph.
also would probably dig into the harness to manage it better since it's a mess and looks terrible and has melted on the exhaust twice during my ownership despite it being continuously ziptied out of the way



From what I hear you probably don't often drive like a grandma ..... and you're engine is not running correctly. Actual gas mileage test needs data collected over at least a couple of tank full's. How do you test it? Throttle costs gas so does "unnecessary brakes. I see a lot of that among "robust" drivers.

As for the fireballs, let's do a thought experiment. Running at moderate to high RPMs and suddenly the throttle snaps shut. Suddenly no oxygen to burn fuel. In theory the fuel must also suddenly shut off or there will be unburned fuel in the exhaust just looking for some oxygen. So ..... why is there fuel in the exhaust system? Does the ECM know what the throttle is doing? What is the TPS telling it or not telling it? Is intermittent Code 22 a symptom related to fireballs?

Your engine harness is melted? It doesn't go close to the exhaust, or it's not supposed to.
cartercarbaficionado JUN 15, 05:02 PM

quote
Originally posted by Yellow-88:


From what I hear you probably don't often drive like a grandma ..... and you're engine is not running correctly. Actual gas mileage test needs data collected over at least a couple of tank full's. How do you test it? Throttle costs gas so does "unnecessary brakes. I see a lot of that among "robust" drivers.

As for the fireballs, let's do a thought experiment. Running at moderate to high RPMs and suddenly the throttle snaps shut. Suddenly no oxygen to burn fuel. In theory the fuel must also suddenly shut off or there will be unburned fuel in the exhaust just looking for some oxygen. So ..... why is there fuel in the exhaust system? Does the ECM know what the throttle is doing? What is the TPS telling it or not telling it? Is intermittent Code 22 a symptom related to fireballs?

Your engine harness is melted? It doesn't go close to the exhaust, or it's not supposed to.


usually I'm driving much more relaxed and trying to hypermile while driving to work which usually means 65 mph windows up no matter the temp and low rpm and low throttle to keep it there with as much coasting as I can. that somehow doesn't change the fuel economy much and doing ~ 15 mpg compared to how I drive it to let's say get halfway across the state to help save a buddies car that blew a tire which is usually foot welded to floor throttle open and rev matching the upshifts (transmission shifts much faster and was doing this to keep a broken dogbone intact for a drive once so it became habit because it made it much smoother) while hitting just before Redline on every shift to keep it In the PowerBand just after upshift usually sitting near 4.5k rpm going 130 mph and getting 10-12 mpg. also usually doing the same pump same station fill method for a fill up and then doing that over a few tanks to average it out. it's usually around 15 mpg. it used to be over 28 for a long while but would overheat constantly
yeah the harness got melted around the ignition coil but has been repaired with Sauter and heat shrink. the issue was that the heat wrap wasn't where it was supposed to be and the heat Shield shifted upwards and was hot enough to scorch a shift cable