easterly81

My 3.0 has had this problem for a while now but is get worse. The truck running great after it warms up. The problem seems to be worst in the winter. The 52 code (knock sensor) is new but i'm assuming that it related since i never get the code if the engine is warm. Lately the hesitation is so bad driving the truck is impossible until it warms up.

The coolant temp sensor is about 1 1/2 years old check out good.

The VAF check out good

The TPS falls in spec but acts strange under vibration. I was thinking of replacing it today, but it doesn't make sense that the truck operation normally when warm or in the summer.

no vacuum leaks

resent head gasket done,the truck has new plugs, wires, distributor, and lots of other stuff. Problem has present before and after.

Getting real frustrated here.

JohnnyCanuck

I wonder if your cold start injector might be suspect?

scope103

When you get code 52, it means the ECU has "lost touch" with the knock sensor, so the ECU dramatically retards timing to save the engine (if the engine were actually knocking and the sensor said nothing, you could blow a hole in a piston). Retarded timing = runs like crap.

Code 52 has nothing to do with engine temp or VAF or TPS or vacuum leaks or plugs, wires, distributor.

The reason you only get it in the cold is because sometimes a wire will contract in the cold breaking a connection, only to re-make it (temporarily) when it warms up. But heating the wiring is only a stop-gap; this problem is only going to get worse.

The knock sensor itself is pretty rugged, and I don't think it fails very often. But the "pigtail" is in a hellish environment and fails often. It's not an expensive part, but you have to get to it to replace it, which means removing the lower intake manifold.

Good luck!

easterly81

Cold start injector--The problem happens in summer when engine is cold just not as bad, also. I live in California so it never really gets that cold. I pretty sure the cold start injector is rarely needed in my enviroment.

What cold cause the horrible hesitation when cold?

mxoliver115

I have the exact same problem. I replaced the ns pigtail, rewired it with a new coax. It didn't help. Put a new harness, wires ,cap,rotor,distributor. Didn't help.tps checks out and so does the AFM. I am suspecting the pair valve other than that I'm at a loss ATM. Pleas let us all know what you find and so will I.

Punchy

PAIR valve only lets outside atmosphere into the exhaust to help burn unburn fuel with the CAT and to keep velocity.
It will have nothing to do with the code 52 what so ever unless possibly your exhaust valves are gone.


Doubtful coldstart injector if it starts fine.


98 percent that any of the following are bad, Pigtail, knock sensor itself or the wire to the ECU.
Its completely independent of anything else, Coax from ECU to pigtail to sensor.
I would assume that during the HG job the pigtail was damaged and the temp rising is expanding the connection or making the wire coating soft and allowing it to connect.


Oliver, I would still think you have a short or break in the circuit your overlooking or your ECU is faulty but doubtful.
The ECU is very forgiving with concerns on the knock sensor except not seeing it (Ohm and signal).

mxoliver115

Ok Ive looked at this 2 ways, is it a code 52 issue that's causing the hesitation or is the hesitation causing the 52? So I've been trying to diagnose them as separate and combined along with other problems that might be causing the hesitation. I've redone the small knock sensor harness twice and the main harness 3 times .I've tested the wire from sensor to ecu and is perfect. So code 52 is either a faulty sensor or ecu.so the hesitation could be caused by?

easterly81

I unplugged the knock sensor pigtail and sprayed tuner wash on the pins then put dielectric grease on them plugged it back in and got lucky. I no longer have code 52. It must have been the temp making and breaking the connection. I still have really bad hesitation when cold. This morning I was ina hurrying to get to work and it stalled three times when tried to take off before it was warm. I had to wait for it to warm up. I'm still at a lose on the hesitation.

mxoliver115

So the hesitation is separate problems to the code. I'm not throwing any other codes so what else would cause the hesitation.

mxoliver115

Well as far as the hesitation a new distributor helped a lot but is still there. When I disable the pair calve it helps a lot which when I tested it I'm getting some blow back into the intake. Tonight I'll test the intake air temp sensor. I'm nott sure what else it would be.

Punchy

Easterly81, Check the EGR system, If its bleading inert air into the intake the same time the cold start injector is on it will cause lag.


Oliver, Sounds like the PAIR reed valves are bad or the vacuum hoses are connected to the wrong VSV (PAIR = Blue).

PAIR valve should only open during decel when the idle switch in the TPS is open (or closed if I have that backwards).


The Knock sensor must be bad then, I have heard engine knock like a diesel engine and not throw a code 52, But when unplugged the Chk Eng. light comes right on.

scope103

Uh, backwards?

All answers are in the Good Book. http://personal.utulsa.edu/~nathan-b...78pulsedse.pdf

Gevo

How come noone has mentioned timing? Perhaps I'm missing something, but wouldn't incorrect timing cause Engine knocking, thus the code? When the engine warms up the computer is able to adjust (electronically advance or retard) the timing enough for it to work well.... ?

scope103

I can't speak for why anyone else didn't mention timing, but code 52 has nothing to do with whether the engine is knocking. Code 52 means the computer can't tell whether the engine is knocking; it might be purring like a kitten.

You can change the timing all you want, but if the ecu has lost touch with the knock sensor (bad sensor or bad wiring), the code won't go away.

Having said all that, mis-timing can cause hesitation (when there is no code 52). But I'm hoping the OP has checked the base timing pursuant to the FSM.

Gevo

Scope, I see. Of course I am not familiar with code 52 but I do understand its specific purpose now. So I assume that there is no code to show if the engine is knocking beyond its ability to adjust for it? If so this would not be code 52, right?

scope103

All I know about codes I read in the same manual you read.

The purpose of codes is to tell you (the driver) about failures (primarily in the emissions control system) that you can't detect with your own eyes/ears. You can't see that the engine is running over-rich. But you can see that the truck has run out of gas, or hear that it is knocking. So no codes for the last two.

easterly81

I have the same problem with the pair valve I have had the hose kinked off with zip ties to bypass it for quite sometime. I unkinked the hose yesterday the engine makes a terrible gurgling noise when deaccelerating. Im guessing the pair valve is bypassing air more now than when i kinked it off, the first time. A strange thing that happened tonight when i was showing a coworker the terrible noise. I noticed the resonator for the pair valves intake was crack where it bolts to the intake is reached down to feel if the back side of the resonator was crack and the distributor shocked the ˟˟˟˟˟ out of me. This i found strange because the distributor, rotor, cap, wires and plugs are all newish. There was no bad connection. I was wondering if this could be related?

The egr bogs the motor down when vac is applied and i double checked the lines today. The vac modulator was replaced 1 to 2 years ago.

Punchy

Code 52 is The ECU cannot see the knock sensor with in 6 rotations.
Code 53 is The ECU is detecting a malfunction through the knock sensor.


Since you also had a headgasket done you might want to look into the crank & cam timing marks again and make sure there right or if the belt tentioner has alow a belt jump. (I may have miss read that you have already done this)


Scope, I couldn't remember if the TPS idle switch opens or closes during decal.

Gamefreakgc

You just described my truck in a nutshell! Noisy PAIR valve (by choice, did you do the ISR mod by chance?) and my distributor shocks me every time I touch it when the engine runs. No ill effects from either on my rig, I'd keep looking if I were you.


Now if your PAIR valve is making tons of noise because it's broken? You'll need to fix it. PAIR valve rarely go bad so I would be ok with a used on in your place, but that's just me and not everyone would go that route.


Vacuum leaks will kill your throttle response, plain and simple. But there's my opinion, add that to the dozen others in this thread.

easterly81

I have my intake box modded and my resonator removed if this is what you are talking about.

The hesitation problem existed before the head gasket. My based timing checks outs. The pair valve is operating correctly but the ecm is sending the signal to activated the vsv most all the time. When the vsv disengages its not consistent. The good book say the vsv should :


so is it safe to say the ecm does not see the rpm or the coolant temp? A lack of either of these two could diffidently cause my problem, correct?