Lack of power and 'missfire' under 3000 rpm 1.7 MHA

[serth]

Evening all,

I've recently put a 1.7 MHA Puma engine into my Mk5 Fiesta Zetec S. Really enjoying the car now, it's really come to life.

However, I have had an issue with what i can only describe as a lack of power/missfire, and it happens 95% of the time below 3000rpm, if it happens at all. Some times the car will be absolutely fine and run like a dream, other times it will be very difficult to drive.

I have changed the following, with absolutely no advance:

Coil pack
Ht leads
Spark plugs
Fuel filter
Throttle body to inlet manifold gasket (was cardboard from previous owner)

So i plugged the car into an OBDII code reader and it threw up 4 codes, but the only one i can think relevant is C1967 - Low fuel level circuit indicator.

The fuel pump/sender has been making a high pitched whining noise pretty much since the conversion, so I'm begining to think it is this.

However, the loom has been hacked into by the previous owner who wanted to build a track car, so there are a couple of crimps in places there shouldn't be etc. Apart from this, and ABS (a seperate error I'm looking into currently) I'm lost on what the problem could be, and I don't want to keep chucking money at it to find i have a dying motor.

There is no oil or water useage, absolutely no mayo on the caps or in the oil, oil level is fine.

I have tried to test the voltage/resistance of various components but not had too much luck. I got resistance of 15.7 on all 4 injectors, 12.14v on the coil pack and 574ohms on the camshaft position sensor.

My next ideas are to replace the TPS (throttle position sensor - which wouldn't give a reading), before probably searching for a fuel pump replacement. So if anyone has any other ideas, please let me know! Is there any other ford with the same TPS and possibly even MAF as the 1.7 puma? And how do i go about getting the fuel pump/sender switched over?

Cheers in advance

 

[Ian G]

Was it good when it came out?

Fuel pump would get worse up the rev range I would think.

 

[serth]

I would have assumed that Ian (I'm guessing you are the same Ian from ZSOC!). I was told it was a good engine when removed however i didnt hear it running. The previous owner wrote me an agreement saying that if it wasnt good then he will give me a full refund, but i don't think it's a massive issue, just a sensor/wiring problem?

 

[748]

O2 sensor?

 

[STEAVIE]

has a problem with the fuel pump on mine was really bad at low revs almost stalling but once you revved it up would drive fine, hard to say for sure if thats the fault you have. also the low fuel level thing is nothing dont worry! k:

 

[serth]

anyone know the approx price for a fuel pump?

 

[STEAVIE]

Get an upgraded one from burtons £80

 

[serth]

Thanks guys,

After changing the MAF and TPS the problem persisted, so i unplugged the lambda sensor and it's been running fine since. Will remove the plug and loom once the car is next in the air and will look into replacing/repairing. I've got 3 lambda sensors from cars for breaking which i will use to see whether it can solve the problem.

I have noticed another issue now, and I'm not sure whether I am hearing things or whether it is something to genuinely wory about.

When i lift off at mid to high RPM in any gear, i hear a sound like a high pitched scratching. It only sounds when the car is in gear, but comes from the drivers side of the engine. My thinking was that it could be a pulley squeeking or possibly a driveshaft on It's way out - it the frequency and speed of the noise increase with the RPM.

Doesn't sound like marbles dropping which would signify detonation...
I tried to get a video but it there was too much wind noise.

Any ideas?

 

[serth]

anyone?

 

[xztraz]

check idler pulleys. they give up sometimes. could be water pump. or worst case cam belt tensioner. rattling around 2-3krpm would indicate the later. Test without the aux belt if you can. rule out some stuff.

 

[serth]

I had a proper listen under the bonnet the other day and it sounded like it could be coming from the power steering pump - located on the back of the engine above the manifold as i have an AC pump on my car. The fluid in the reservoir seems to be bubbling, almost as if it is boiling (i need to remember to check the temperature).

Is this something that is likely to be the culprit? Tensioner pulley came from a friends 1.7 engine which had no noises/issues so hopefully that's ruled out. It almost seems to be in time with the revolutions of the aux belt - every time i see the white lettering whirring past i hear the noise in time with it.

Aux belt was new 700ish miles ago...

 

[PaulQ]

Had you not said that the belt was new, I would have suggested that it was on the way out. Years back I had a Cortina that developed a tick-tick-tick sound. Not long after it went (No damage, it was a low-compression engine.)

Have you had a compression test?

 

[serth]

I bought a compression test kit to do the above but it wouldn't screw into the plug hole, even with the supplied adaptor on.

I came to the conclusion that the holes were cross threaded, but as an after thought, if the plugs fit fine, then i can't see this being a problem...

It would be good to know what the compression is like though so I know whether the engine is a keeper or not...!

 

[xztraz]

if you take of the aux belt and start the engine (for a short time since you have no water circulation) you can at least sort out if it's the cam belt or aux belt causing the noise. and also inspect the pulleys and the belt. i would start with that. not much work.

 

[serth]

View My Video

The above is a link to the noise that i finally managed to capture on video. It's not quite the noise i mentioned above but I believe it could be all part of the same problem. This noise comes from the top of the cam belt cover region, I have an aircon pump on the front of my engine so the PAS pump is at the back just above the manifold (ish).

any suggestions? Is this normal?

 

[faster _ faster]

Don't know if you've checked or listened out for it. But check the exhaust manifold gasket. Known for making the tick sound and extra air in the exhaust will screw up the lambda.

With regards to the fuel system you were talking about does this all happen when you're fuel level falls below a certain point? If so I can honestly say, take the tank off and inspect the swirl pot pickup. Had a mk4 astra with this kind of problem would drive like it had no fuel pressure when it was below half tank, turns out a snail got into the tank, obviously died and it's shell blocked the pickup for the swirl pot.... so check that....

 

[serth]

Cheers for the reply mate. Problem solved for now - one of the 4 lambda wires had come un-crimped. But I will remember your advice for future issues that may arise!