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Odd Td5 Issue


Phil
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My '02 110 has an issue which appears to be related to the temperature in the engine compartment.

Beyond a certain temperature and when the engine is under higher load (eg climbing a hill at motorway speed) the temperature gauge will periodically rise to maximum and the engine power will reduce, both for a second or two only.

I've research the symptoms some time ago before identifying the temperature factor. On the basis of advice then received I've replaced the relays and ECU earth in the seatbox, and fiddled with the wastegate all of which were suggested solutions.

I can demonstrate the relationship with temperature; if I roll down the snow blind to cover the radiator grille and then drive the symptoms will appear, if I roll the blind up and drive they will not appear.

Can anyone suggest what might be causing this because I've searched and searched, and I'm baffled.

All help gratefully appreciated!

Phil.

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Dont know alot about TD5's , but i have read they suffer from injector harness, turbo actuator seizing, Turbo Wategate Modulator , and MAF and MAP sensor problems,giving missfire and loss of power problems.

Have you had it pluged in to see if there are any fault codes recorded?.

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Dont know alot about TD5's , but i have read they suffer from injector harness, turbo actuator seizing, Turbo Wategate Modulator , and MAF and MAP sensor problems,giving missfire and loss of power problems.

Have you had it pluged in to see if there are any fault codes recorded?.

I have and there weren't, or at least none that shed any light.

Phil.

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Andy, I agree, it does appear that the power is reduced because the engine seems to be overheating. I don't think that is actually the case, certainly there are no signs under the bonnet. The symptoms appear either on hot days (say 20C+) or if I roll down the snow blind. The vehicle has to be fully warmed up and typically under 'heavy' load (eg going uphill at 70mph). The temperature gauge will be at its usual position just below half-way, it will suddenly rise and the engine power will drop, after a second or so all returns to normal.

A guess is that the higher temperature in the engine compartment causes something to behave as though the engine's overheating and to cut the power, however, I've no idea if that's likely nor what it could be. I've seen others describe the same symptoms as having been cured by replacing the ECU earth and/or relays in the seatbox; I've done both those things but that hasn't cured the issue in my case.

Hate this sort of thing!

Phil.

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Thanks, rocky, I think the radiator's fine; I flushed it through a month or so ago. If the thermostat is sticking should I notice any other symptoms? If there are no other signs, what's the best way to test it? I guess they're not expensive so perhaps just replacing it is easier.

Phil.

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Thermostat is fine.

I am still of the opinion that it is something electrical, that is being affected by temp rise, i would take out youre MAP sensor on the inlet manifold and check it is not covered in oil. Its the sensor on the Air intake manifold on a Td5. It is just 2 x 8 mm bolts

Also there is this relating to the MAF sensor:-

From the workshop manual.

The MAF sensor is located in the intake system between the air filter housing and the turbocharger. The ECM uses the information generated by the MAF sensor to control exhaust gas recirculation (EGR).

The MAF sensor works on the hot film principal. The MAF sensor has 2 sensing elements contained within a film. One element is controlled at ambient temperature e.g. 25 °C (77 °F) while the other is heated to 200 °C (360 °F) above this temperature e.g. 225 °C (437 °F). As air passes through the MAF sensor the hot film will be cooled. he current required to keep the constant 200 °C (360 °F) difference provides a precise although non-linear signal f the air drawn into the engine. The MAF sensor sends a voltage of between 0 and 5 volts to the ECM, proportional to the mass of the incoming air. This calculation allows the ECM to set the EGR ratio for varying

operating conditions.

Inputs / Outputs

The MAF sensor receives battery voltage (C0149-3) via the ECM on a brown/orange wire. Signal output on a slate/light green wire from the MAF sensor (C0149-2) to the ECM (C0158-11) is a variable voltage proportional to

the air drawn into the engine. The MAF sensor is provided an earth (C0149-1) via the ECM (C0158-20) on a pink/black wire.

The MAF sensor can fail or supply an incorrect signal if one or more of the following occurs:

• Sensor open circuit.

• Short circuit to vehicle supply.

• Short circuit to vehicle earth.

• Contaminated sensor element.

• Damaged sensor element.

• Damaged wiring harness.

• MAF sensor supplies incorrect signal (due to air leak or air inlet restriction).

In the event of a MAF sensor signal failure any of the following symptoms my be observed:

• During driving, engine speed may dip before recovering.

• Difficult starting.

• Engine stalls after starting.

• Delayed throttle response.

• EGR inoperative.

• Reduced engine performance.

• MAF signal out of parameters.

In the event of a MAF sensor failure, the ECM will use a fixed default value from its memory.

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I checked the wiring to the MAF sensor when I replaced the sensor unit and it appears intact. The injector harness is original, I've checking it and there is no sign of any oil contamination.

Thanks,

Phil.

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Is your fuel pump noisey?

I think i read you have disconected the Red plug from the ECU and checked for oil contamination?

Have you got a catalytic converter in youre exhaust?

Do you change your fuel filter regularily?

Have you checked the small filter on the inlet side of the fuel pressure regulator?

I see that you had this same problem back in June of this year http://forums.lr4x4.com/index.php?showtopic=57697, and you "cured" it, as the waste gate was sticking, not the same problem again?

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Is your fuel pump noisey? - no more than it's ever been

I think i read you have disconected the Red plug from the ECU and checked for oil contamination? - yes, that's right

Have you got a catalytic converter in youre exhaust? - yes

Do you change your fuel filter regularily? - yes, every 6,000 miles

Have you checked the small filter on the inlet side of the fuel pressure regulator? -yes, and I replaced the regulator a couple of months ago as it was leaking

I see that you had this same problem back in June of this year http://forums.lr4x4.com/index.php?showtopic=57697, and you "cured" it, as the waste gate was sticking, not the same problem again? - that didn't cure it, I was naively optimistic, nor did the ECU earth and seatbox relay replacement steps that were suggested in posts around that time

Thanks,

Phil.

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That's an interesting suggestion, how would a failing converter cause the symptoms?

Phil.

As the cat gets hotter underload the ceramics restrict the flow more causing restriction in gas flow, causing engine temp to rise causing ecu to go to limp tempoarily, engine temp and flow of gas decreases, cat open up slightly as it gets cooler band let flow through again.

I am really guessing here, but it should be fairly easy to eliminate by as i said droping the exhaust from downpipe and trying?

Maybee a grown up will come along soon, and shoot me down in flames, wouldnt be the first time!

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