Clean engine= happy engine

 

It was pretty clean in there when I changed the knock sensor and sub harness last year. Even the intake valves were nice and shiny.

 

well HELL, the problem is back! Intermittent power delivery. Throttle response is spotty. Pressing down on gas pedal with no feeback or some limp mode type symptoms then BOOm the power comes in. In all gears and it's worse at colder start

 

I have no idea and am guessing, but: Is your car equipped with a Turbo?

 

NA. Just exahaust and plenum spacer. Here is what I have done so far. Cleaned MAF, cleaned TB. The problem is absolutely NO CEL When I had to replace my Camshaft sensors a year ago I never got a CEL and replaced them and fixed the issue I had at the time which is similar to what i have now but with camshaft sensors going out itll kill power as you're accelerating. This issue I have now is only if I am cruising with foot on gas and if I accelerate it acks like I am not even pressing the gas pedal I have to press down, let off and then press down again for it to react if that makes any sense. I am thinking it MIGHT be the TPS but wouldn't that throw a code or can it go bad without a CEL?

 

I am going to check the TPS and APS sensors/ might be the TPS but damn it have to buy a new TB for that. sucks not sold separately

 

Take it to some one to do a proper diagnosis.

 

Or find a real good friend that will let you swap parts till you find the problem. Ie. Maf sensor.

 

sounds like throttle body... try replacing it

 

It might actually be your pedal. I remember reading in the Titan forum about a guy who had a bad pedal and it did not produce any codes....but that was a while ago, I'd never find it now.

 

All this needs is a really good scanner and a brain. The scanner needs to display the full OEM datatream and pull mode 6. Genysis, Snap-On, Launch will have this. Somewhere in that datastream a value is not going to make sense within the driving conditions during the problem. If nothing is suspicious on the datastream then mode 6 needs to be checked, this is RAW data that needs to be converted to understand it. It has all the individual tests for each component, so you can see if something is close to failing but not enought to set a code. Of course it is still possible and probable that you have an actual mechanical issue and not sensor failure.

I've got an annoying dead spot in first gear only, part throttle only I think. I get too much wheel hop if I go WOT so it's hard to tell if present at all throttle angles.

Some light reading to make your future diagnoses easier, great stuff and better than the school I went to.

autoshop101.com go to the technical articles.

Good luck!

D (actual mechanic)

 

Update:

The temp here has been cold below 50 and usually in the 20s and 30s so the "ICE" mode was showing on the guage. But it finally got back up to the 70s and 80s as of yesterday and guess what. The car runs fine now. My guess is it's going into some kinda limp mode when it's cold and considered "ICEY" to the car. Is that possible? I find it strange but the next two days its been in the 70s and the car runs perfectly fine. I tried to duplicate the issue but it just drives normal which makes me happy but I have had the car for over 10yrs and never noticed this issue when the temps get near freezing

 

Refresh my memory, did you ever try some dry gas?
There's no limp mode for cold weather lol.

 

Colder air means more 02 content for the volume going through the intake. Temperature can also change resistance in electrical circuits, expanding and contracting wiring and making a poor contact better or worse.

So its possible that your ECM is getting an false signal and generating incorrect fuel trim for those actual conditions resulting in hesitation. The colder air then makes that calculation work but it will still run incorrect at higher temperatures. Check the IAT and ECT when engine is fully cold, they should read the same.

 

I have not read every post in this thread, but:

I had a Mitsu tt with the same symptoms. Ckd the intake manifold coolant temp sensor for resistance. It was out of range. Cheap diy fix, ran like new after that.
Good luck!

 

Sounds silly I know but no lie. After the temp went back to the 70s the car ran perfectly, no hesitation what so ever. How exactly does one check for "dry gas?"

 

Sounds about right and thanks I will check that

 

That's true, the ecu might think it's colder out than it actually is. Dry gas is just isopropyl alcohol that's made for removing the water in your gas tank....if there is any. It's the cheapest and easiest thing to do.

 

so the weather has been in the upper 70s and 80s and the car runs flawless. thankfully for me it doesn't get cold here in TX often

 

Put a bag of ice on the MAF (The IAT function is built in there) and see if you can recreate the problem.