Extremely Low Mpg...why???

rideapony · May 24, 2017

I have doubts about that theory too

Deleted member 215073 · May 24, 2017

You really should look at replacing the O2 sensors. They do have a replacement interval.

Gear grabber · May 24, 2017

I would say your 9'' idle vac. is low.
Duration is only 221/225 at .050.

rideapony · May 24, 2017

I think so, new O2 will be installed.

I'm looking for information about what would be the vacuum this TFS stage 1 cam generates but can't find a definite information.

What causes that low vacuum number? Would be the typical reasons like a vacuum leak, improperly adjusted valves, etc???

Also I searched on the Trick Flow Specialties webpage the specs for this cam and says "Calibrated air flow meter required" I'm assuming they mean that this cam cannot be used on speed density cars, correct?.

The specs sheet used to say "24 lb injectors are required" I don't see that suggestion anymore.

Any help will be appreciated!!!

Thank you all!

General karthief · May 24, 2017

I'm not as tech savy as most on here but I would try this,
With a vacuum gauge attached, pull the spout and bump the timing up a couple degrees, you mentioned bumping timing in your first post so I'm guessing your at 10 dbtdc, try 12 and see if this raises you vacuum reading, could go to 14 if vacuum still rises but no more that that, shut it off, disconnect battery cable for a few minutes then stick spout back in and connect battery cables and drive it around to get up to operating temp then check codes.

rideapony · May 24, 2017

Yeah I was running 15 degrees but set it back to base timing of 10 deg to run all the tests with my code reader. I will try what you suggest and will see how it works.

Thank you!!!

Mustang5L5 · May 24, 2017

I have a TFS1, but have yet to install it. But yes, a MAF sensor is needed, can't run on SD.

Quite a few guys run that cam, you can prob get some input on what they see for vacuum.

Noobz347 · May 24, 2017

Mustang5L5 said:
can't run on SD.

troofs

The OP already stated MAF though:

rideapony said:
I did try two different MAF sensors and give constant cleaning with MAF cleaner. I'm reluctant too to replace parts arbitrarily first because probably unnecessary cost and second you loose track of what really solved the problem.

rideapony · May 24, 2017

Yeah I know, that cam is very popular and really hope to get some vacuum numbers published, that will be helpful.

Thank you!

rideapony · May 26, 2017

Hi all,
I still working on the initial problem "Extremely Low MPG... Why???"

If I may ask you about another I think not normal issue that is happening.

My idle hangs up at about 1K for two to three seconds then it drops to idle speed, this seems to be a normal behavior on maybe all Stangs at least on fox bodies.

The problem I see is more complex. When driving and if put the tranny in neutral but the car still rolling my idle goes up to about 1,500 rpm, then when it gets to a full stop the idle drops to 1K for a couple of secs then drops to normal idle. But there is more, while driving on a fairly flat road very slowly and I get off the throttle the car starts speeding up until my idle is about 1,500 rpm and sometimes a bit higher. I press the brake to slow it down and it starts speeding up again.... What the heck is going on??? It acts like a cruise control, obviously it is not because the cruise control is inoperative and the cable is off the TB. That's a weird behavior and would like to hear from you about how can I correct this issue too as this could be part of the excessive fuel consumption.

Thank you all!!!

Noobz347 · May 26, 2017

You could benefit from running The Surging Idle Checklist from top to bottom.

You can find a link to it in "The Useful Technical Thread Index" located in the Technical forum:

https://www.stangnet.com/mustang-forums/threads/technical-thread-how-to-index.808661/

rideapony · May 26, 2017

I went thru that checklist before with no results. I'll do it again...

Noobz347 · May 26, 2017

Post the results of each test as you go.

rideapony · May 26, 2017

Update:
I'm going thru the Idle surging checklist. I set up the throttle plate stop screw at 0,010" plus 1.5 turns, TPS at 0.991 Volts. I haven't started the car yet to verify the base idle rpm with the IAC valve disconnected.

Prior to this, I put some smoke into the manifold to check for leaks. Smoke was coming out of the EGR valve, not exactly where but it was coming out all over the valve. So guess what??? I removed the darn thing!!!! I had a 5/8" plate so I did the whole thing...

At this point I don't have a TwEEcer to remove the EGR function from the ECM, but I will follow Mustang5L5 advice from another thread about NOT to use the EGR delete plug so the ECM disables the EGR function with an error code avoiding possible detonation by the ECM adjustments when trying to fool it with the plug. I know I will be seeing the CELL flashing which I really hate but for now it will be like that. I'm I doing this the right way???

On the EGR removal subject I have an interesting question based on these next scenarios:

Scenario No.1).- If I remove the EGR and before I start the engine I use the plug to fool the ECM, and then I start the engine. There should be no CELL light so the assumption is that the ECM thinks the EGR is hooked up and ready to run so the ECM starts making adjustments to timing and fuel.

Scenario No.2).- If I remove the EGR and start the engine without using the plug. The CELL will start blinking and as I understand the ECM once it senses the absence of the EGR it will throws an error code which according to Mustang5FL5 the ECM disables the EGR function.

So here is the question: If I follow scenario No.2 and if after the ECM has an error code and has disabled the EGR function I use the plug to shut down the CELL blinking light the EGR will remain disabled?

Please confirm or reject the theory on my question.

Thank you all a bunch!!!!!

rideapony · May 26, 2017

... No EGR...

Mustang5L5 · May 27, 2017

I need to update some of my old info. Yes, just leaving it unplugged will tell the ECU it's not functioning and disable the logic. You will get a check engine light, but no timing/fuel will be pulled at part throttle.

As for the resistor packs. I may be incorrect in how they function. They may be set at a resistance that tells the ECU the EGR is closed all the time. It may signal the egr to open, but since it shows full closed, the ECU may never change fuel/timing strategy.

For now, just leave it unplugged. I'd research the resistor packs s bit more as my previous info may be wrong

Noobz347 · May 27, 2017

Progress.... Good work.

rideapony · May 27, 2017

Thank you guys!!!

I'll keep going on this troubleshooting these two issues "Excessive fuel consumption" and "Odd idle behavior" and will post updates on how it goes.

Of course fresher information you guys might have will be helpful. I'm always interested on learning.

Thank you all!!!

rideapony · May 27, 2017

Mustang5L5 I was going thru your old postings on this and foundthis statement, not sure if there has been any corrections based on more research and results:

Thank you!!!

rideapony · May 27, 2017

And what is this CANP solenoid anyways...?

Extremely Low Mpg...why???

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Deleted member 215073

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wonder how much it would cost to ship you a pair

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That is…until I whipped out my Bissell

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That is…until I whipped out my Bissell

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