Engine cutout at Highway Speeds

A month ago my V6 4.0 began having harder than normal starting and idling rough. It would also cutout for a 1/10th of a second while driving highway speeds. The cutout is for a split second and only happens at speeds 55-60mph. I notice it more when in cruise control. My rpms dont drop when it cuts out, no check engine lights or codes (scanguageII).

I cleaned the MAF and throttle body and startup and idle seem to be better, but it still cuts out. I've kept my eye on the rpm gauge when it cuts out and engine doesn't seem to skip a beat. Someone told me it could have something to do with the transmission. Could it have anything to do with supercharger?

I also put in the walboro 255 pump upgrade - only couple thousand miles on it. Cut out also happens with full tank of gas, cold and warmed up engine. Also thinking it could be the throttle position sensor.

 

I'm leaning towards the Throttle Position Sensor (TPS) Unplug it and plug it back in; could be a little corrosion on the pins. Also check for any pinched or burned wiring especially around the exhaust

 

Will go do that now. Should i throw some dielectric grease in there?

 

Do you have an aftermarket intake? Some people have trouble with wind buffeting at certain speeds and not getting air into their aftermarket intake.

 

You could. I bet you need a new TPS sensor but see if cleaning the pins to get a good connection works first.

 

Pulled pin connectors on throttle body and MAF and everything was clean and shiny. Blew em out with a can of electronic duster air and replugged. I have a k/n intake but have 20,000 miles prior to this cutout with it installed.

 

Fuel Filter?

 

New fuel filter was put in 4500 miles ago when i installed the walboro 255 fuel pump kit. It's weird, it only happens between 55-60 mph at cruise rpms. I can floor it all day and no cutout.

 

I'm still leaning towards a faulty TPS.

 

It looks like the TPS is riveted to the throttle body itself. I take it you need to buy the whole assembly and not just the sensor. I saw a thread on how to test your throttle body with a digimeter by moving the throttle plate manually. I'll have to go research. I haven't used a digi-meter in years, anyone know what setting to use/what to look for to test throttle body?

 

What's this wind buffeting?, about six months ago i cut more of the front inner fender on the passenger side, now there is a big gap. Maybe disrupting the air flow up to the top of the wheel well into the enginge bay? I shall investigate my dear Watson.........(how, I do not know)

 

I'd be looking at changing out the 02 sensor(s) anyway. It could also be an ignition coil going bad; It would be nice if you could try a different coil on each of the plugs to see if that fixes it. Assuming it's not the TPS.

Again, look around carefully for pinched or burned wiring and brittle vacuum hoses, always.

I don't think your custom air intake has anything to do with it unless the hoses are loose.

 

One of the little coolant hoses that connects to the back of the throttle body is leaking and some of the coolant is shooting back onto the fuel rails of the injectors. I wonder if this is causing problems. Will change hose out and see. Tuesday i will test TPS, found how to check with digimeter.

 

My truck is doing this too, waiting to hear what the fix is.

 

Do not over tighten the clamp.

 

Changed the small coolant hose and i did use worm gear style hose clamps. The original tube was leaking at both ends with those oem spring clamps.

Today i had the engine cutout again a few times going 55 mph cruising. I have an appointment on the 14th to meet with a toyota tech and do a test drive and diagnose. I already gave a list of the mods i have and they're cool with it (My 5 yr powertrain warranty will run out this August and only got 33,000 miles so far). Going to put in a bottle of Heet gas treatment to see if there may be some water in the tank. When i put the fuel pump in I probably had 6 gallons in the tank and it looked really white and murky.

I already had an o2 sensor changed out when my truck was completely stock, so may be related. Still no Check light. My scanguage shows all these pending codes but they all seem to be emission related. No codes that start with "P".

I did notice today some "very slight" fluctuation in the throtle and actual engine response, and stronger surging at stop light. I'm going to make sure they fully test the Throttle Position Sensor.

 

Isn't it common for oiled filters to cause the maf sensor to go bad?

That's what I would be looking at. Especially if you suspect you might have over oiled it.

 

Cleaned the MAF a couple of weeks ago, was pretty clean already. The K/n filter has not been reoiled since I put it on and that was roughly 24,000 miles ago. Never had a MAF prob before.

The Iso Heet gas treatment went in this morning (figured why not give it a try), and honestly driving home in stop and go traffic it seemed to run much smoother, especially my idle at stop lights (I'm probably trippin'). We'll see when i hit the highway to town if it cured the cutout. Haven't made time to pull coils and plugs or test tps yet. Something always comes up. I need a cookie....

 

Took truck in to my Toyota dealership and spoke with the tech who was going to work on my truck. 4 hours later they call me and say that they didn't work on it cause it is going to take them atleast a day and they recommended me to someone else to take my truck to. (An ex toyota tech who specializes in modified vehicles). So need to set up another appointment, the funny/frustrating thing is my truck is running great and haven't had the cutout for a week and a half now.

Someone kick me in the goat ass!

 

^Isn't that the way it always works lol..