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Stalling and poorly running Duratec


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Hi everyone -

 

The Caterham has been sitting in the garage the last 2 months due to summer travel and work. Since we had a cool weekend over Labor Day, I elected to get it out and take it for a drive which I've been eager to do, despite having a lot of other priorities. Sometimes you just need a drive you know? Anyway, the start up was fine - it's been on a battery tender - and ran ok the first 5 miles or so. After that it started sputtering, backfiring, was down on power, and felt like it was on the edge of stalling. I got into a parking lot, turned the car off, and popped the bonnet. All looked fine. No smoking, no fluids spraying everywhere, looked totally normal. It started right back up so drove another couple miles to the local Caffeine and Octane. I spent about 2 hours there then left to get brunch. After leaving, about 3-4 miles down the road, the same thing - could barely keep it running. Ate brunch, then on the way home, same thing. It seems to start a death gurgle and will stall once it gets warmed up. When it stalls it doesn't want to start right away. If you turn off ignition and then turn the key back on it will start up right away. I was able to replicate the stall in the driveway just by mashing the throttle a bunch - it seems to stall out when the RPMs are falling after you give it some throttle.

 

I took out the lambda sensor, looks fine. I took out the spark plugs, all look fine. The fuel level was about 50% but filled it up with fresh Chevron 93 octane (best I can get) and still the same issue. I've unplugged the ECU from the loom, let it sit for 5 minutes, then re-plugged it in which is supposed to reset it, but got the same poor running/stalling result. The plugs in it are ITR5F13 which I think came with the motor when I got it (crate motor). The motor is a Duratec 2L using the stock MBE 992 ECU from Caterham. Standard 180hp build with stock Caterham parts, nothing fancy.

 

Any ideas? I've ordered a new set of plugs, the BR7EFS which seems to be a common choice and plan to try those when they arrive on Wednesday. I also ordered the MBE CAN cable, which I don't have, so I can connect my laptop to get some data. My hunch is the 992 ECU needs to go and I need to get a better ECU solution, maybe the 9A4, with SBD's Duratec map.

 

It's weird this started suddenly - it's only got 500 miles on it and the last time I drove it was running pretty well, minus the normal surging/poor idle I've always had.

 

Dan

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Yeah fuel pressure would be something to check. Possibly clogged fuel filter.

 

Does it feel like a cylinder is shutting down? The symptoms sound like when i was losing spark due to a lose wire on my ecu. Engine would run rough, unburnt fuel found its way into exhaust cause poping and backfires.

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Yeah fuel pressure would be something to check. Possibly clogged fuel filter.

 

Does it feel like a cylinder is shutting down? The symptoms sound like when i was losing spark due to a lose wire on my ecu. Engine would run rough, unburnt fuel found its way into exhaust cause poping and backfires.

 

I don't have a way (or don't know how) to go about checking fuel pressure. Will have to Google that tonight when I'm in the garage putting the new plugs in.

 

The motor has always popped a little bit, but just assumed that was normal. I'm suddenly wondering if maybe it shouldn't be normal. On Sunday when I was driving to C&O it felt a lot like a cylinder shutting down so think you're onto something.

 

My general line of reasoning has been fuel, air, or spark.

 

1) Air I think is fine - I worked through some TPS issues before and that made things better and none of that has magically changed.

2) Spark - the plugs I had in there were 5's and I'm moving 2 rungs colder to 7's. Caterham recommends a 6 on the heat index, but folks reported better starting characteristics with the 5's. And the TR6-AP's were impossible to find, even on Amazon. I didn't think plugs made that big of a difference, but guess I'm learning something through this process.

3) Fuel - the car sat with a half full tank for 2 months, but the gas wasn't cheap unleaded. Given the motor has 500 miles on it I'd be surprised if it's built up some kind of blockage. Think it's worth dumping in a bottle of fuel cleaner into the tank and letting it run?

 

Dan

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I follow that same reasoning

 

So if it was me I would confirm that I don't have a rag or something stuck in the intake manifold partially blocking air to one of the cylinders. This could explain a potential shutdown under load.

 

I doubt it's the plugs themselves, from my experience they may effect performance, but what your describing sound like there would be visible damage to one or more. I would still confirm each is sparking.

 

Fuel, not sure in the case of the caterham, but my fuel cell has foam inside. I've heard of a number of people with foam blocks in the tank that after the first few tanks of gas sloshing around and loosening foam particles that they eventual settle to the bottom of the tank and then get pulled through the fuel filter and either clog it or find there way into the injectors clogging those. Same could be said about particulates in the fuel lines from making the lines that get flushed thru to the injectors.

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Dan before you do any replacement of any the parts & pieces take your car to your local tuner. Obviously your getting spark, your getting fuel and your getting air. The car is cold starting fine so everything your saying is pointing towards a tuning issue in my opinion.

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Hi all - thanks for all the suggestions so far! Here's a quick update on progress.

 

- I got the new BR7EFS plugs and a gap measurement tool in the mail today from Amazon. I put those in tonight, .026 gap on all of them. No significant difference I can tell... because I did an oops.

- The coil pack on one of the cylinders wasn't seated all the way (despite me pushing all the way down on it and it being torqued to 10 NM per spec) so when I fired it up after changing the plugs there was a LOT of fuel leaking from the exhaust. I didn't see it at first cause I was on the other side of the car, but then started to smell it. When I looked over I had a holy crap moment and the car stalled right before I made it to the ignition to shut it down.

- To figure it out, I took the temp with my IR thermometer on all the exhaust headers and #3 was 20 degrees less. I re-attached the coil pack for #3, torqued it down to spec again, and fired it back up. No leaking fuel this time...

- However, it will run ok for a minute or two then the pulsing starts and ultimately will stall shortly after. Not sure if that's because of the extra fuel now being in there, or what.

 

I'm really starting to think this is an ECU issue. Ever since I've had the car the idle has been very difficult to get right and it's been tempermental when it runs. There's always a slight pulse in the oil gauge and you can hear the engine note pulsing a bit. Unfortunately, the MBE 992 ECU is locked from Caterham and can't adjust it. The SBD CAN cable will be here tomorrow according to DHL's tracking website so I can attach a PC to it tomorrow and see what the measurements are. Will post more once I get the PC on it....

 

Thanks again for all the help. I'm still very much in learning mode about a lot of this stuff.

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I do not feel it is a ECU issue , Tunes dont go bad and in 99.9% of the time if a ECU goes bad its wont start

 

I would use the Autolite AR103 plugs , In all the Duratec Engines I have built dynoed they have proven to be the best but I dont feel plugs are your issues either

 

Use a volt meter on the front o2 , see what the voltage is doing , I feel you either have a Vac leak or a bad front o2 sensor , I would put in a new front o2 and go from there

 

If you do the front o2 test make sure you take the Batt loose for 5 min or so before testing it , you need to have your meter working when you start the engne so you can watch it from a start

 

Tom

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I do not feel it is a ECU issue , Tunes dont go bad and in 99.9% of the time if a ECU goes bad its wont start

 

I would use the Autolite AR103 plugs , In all the Duratec Engines I have built dynoed they have proven to be the best but I dont feel plugs are your issues either

 

Use a volt meter on the front o2 , see what the voltage is doing , I feel you either have a Vac leak or a bad front o2 sensor , I would put in a new front o2 and go from there

 

If you do the front o2 test make sure you take the Batt loose for 5 min or so before testing it , you need to have your meter working when you start the engne so you can watch it from a start

 

Tom

 

Thanks, Tom. Dumb question - where's the O2 sensor? There's the TPS near the intake, then there's the MAP (MAF?) sensor in the plastic plenum, but that's all I know of...

 

Dan

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- The coil pack on one of the cylinders wasn't seated all the way (despite me pushing all the way down on it and it being torqued to 10 NM per spec) so when I fired it up after changing the plugs there was a LOT of fuel leaking from the exhaust. I didn't see it at first cause I was on the other side of the car, but then started to smell it. When I looked over I had a holy crap moment and the car stalled right before I made it to the ignition to shut it down.

 

This seems odd. A single injector shouldn't be inputting that much fuel at idle/very low load. I wonder if the injector is failing and sticking open, thereby dumping far too much fuel into the cylinder?

 

-John

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What about a blocked PCV valve or something like that?

 

Dave

 

Hey Dave, good idea. I did some reading and think you may be right (or very close). There are two things that lead me to that conclusion:

 

1) I've had a tiny bit of oil seeping out between the oil pan and the block. I resealed the oil pan once myself and paid a mechanic to reseal it the second time. It was fine for a while, but now seems to be seeping again. From what I've read, if the pressure in the crankcase goes too high it could push the seal out and let oil seep through. That seems to fit with what the engine is doing now.

 

2) Way back when I did the build I had a crate engine shipped to me from Ford. It came fully dressed and the PCV valve had this black plastic tube over it. I tried like hell to get it loose - finally got it off - but not after I yanked on it with a pair of vice grips. Hindsight being 20/20, I suspect while I was fighting to get the tube off I may have damaged the valve.

 

3) The oil pressure gauge fluctuates up and down just a tiny bit at idle. I suspect the oil pressure is going up and down as the crankcase gets overly pressurized, then unpressurized to a normal state, then back to being overly pressurized, and so on.

 

I've got a PCV valve on order from Ford, but won't be here until Friday which is (of course) the day I can't go pick it up. Chances are I won't get to put it on until next week sometime.

 

I've also got the SBD USB-CAN cable on the way. It was supposed to be here on Friday last week but the tracking website updated Saturday morning saying it was still in the UK. Tracking now says it's out for delivery today, but it's almost 7:30pm and suspect it isn't coming today either. I'm not overly impressed with DHL.

 

Dan

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DHL came through and the SBD cable arrived! Better late than never.

 

I attached it to the car and did a quick capture. The car idled fine until I started working the throttle a bit. It started it's normal surging once I took my hand off the throttle which you can clearly see in the graph from the data towards the end. It looks like the battery voltage, the ignition advance, and TPS vs Speed ign + Trim all go haywire.

 

I'm not sure exactly how to interpret it, so I've uploaded the data to my Dropbox account. Links below for the lsn and lsn.dat files if you're so inclined.

 

https://dl.dropboxusercontent.com/u/14439357/2016-09-12%20Duratec%20logging.lsn

https://dl.dropboxusercontent.com/u/14439357/2016-09-12%20Duratec%20logging.lsn.dat

 

Dan

2016-09-12 Duratec Tuning Graph.jpg

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Not sure which fuel rail you are using but the one with the round cross-section has a round pulse dampener brazed to it. Ford eliminated it on the one with the rectangular cross-section. I have heard that it doesn't make much difference but maybe your experience suggests otherwise. I am inclined to agree with the fuel pump probability. Are you running a swirl pot in the fuel system?

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