Strange problem.

[Customaniac]

Folks.

66 plate Custom, 2.2, 126k miles, I'm the 4th owner. Changed the oil and oil/air/fuel filters at 125k, about 6 weeks ago.

The orange light was on from the end of last year and was diagnosed as p0404, egr fault. Due to a protracted illness I couldn't do anything about it but the van ran as normal. Had the van in for MOT 4 weeks ago and while it was in they changed the egr valve as the original was chocked solid. Since then there's an odd (to me) problem that has me baffled.

Under light acceleration there's what I can best describe as a momentary but regular hesitation, almost as if the fuel is blocked, then unblocked, then blocked, then unblocked. It's incredibly regular, almost metronomic, and I can hear and feel the engine "surging", for want of a better word. Put the foot down hard and the van is away faster than a Yorkshireman when it's his round, but under light driving the surge is always there.

Had the van back to the garage last week and took the mechanic who did the work out for a run. He had his laptop connected to the obd port and he heard and felt the problem as clearly as me but his laptop didn't detect any faults at all, the only issue being the dpf was blocked somewhere in the region of 50%. At this point I openly admit to knowing nothing about dpf's and regens, but apparently my driving style, steady away up to the speed limit and get it in top gear asap, hasn't helped, so on his advice, and with perfect timing as I went to a "vanlife" meet last Friday, I gave the van some stick down the A1 to get it hot enough to regen.

I don't know if the surging problem is anything to do with the egr or the dpf or it's just a coincidence but the van was running as sweet as a sweet thing before the MOT/egr valve swop, so I admit to being baffled by it.

[metalworker0]

The only way we are going to get to the cause of the problem is ; you use forscan and drive and monitor, as you go, taking snapshots at different revs. light acceleration .. heavy acceleration etc

The forscan software will tell you what is happening under those conditions.

for instance on medium or hard acceleration - the EGR should be closed, and it will be showing as a percentage how open it is, that's if it is open. when it should be closed.

You have a new EGR valve .. but is it a cheap chinese one or a good make like pierburg or gen ford. as well as the EGR you have a throttle plate ... im not quite sure how this works , but i imagine it can get covered in gunge just like the EGR did .

is the turbo actuator working properly - forscan will tell you that
are you loosing boost pressure- forscan will tell you that


Maybe forscan will give you more info.... that's the only way we can get to the bottom of this ..is you learn diagnostics with forscan. otherwise you're taking it into a garage all the time £££££

Forscan
if you have forscan you would have more info than just fault codes.

as regards reading codes

NOTE: you can use forscan to get correct fault codes with proper DETAILED explanation of them - a generic fault code reader may be somewhat misleading, or doesn't work (or we on the forum are unfamiliar with it)_you can see a lot more with forscan. like live running data etc of all systems, everything .. ABS signals, EGR open percentages, pressures, temperatures , graphs

"Forscan" is FREE software that you download to a laptop..you buy the interface cable -- this is just the cable, you need a laptop)
You can join the forscan forum ..again free, to get the software and more answers.

https://forscan.org/forum/

all the best.mark

[Customaniac]

Update:

Had to buy a new laptop as my old one has died, downloaded Forscan to it.

Had it connected to the engine while parked on the drive and all looks fine, no fault codes at all. If I go for a ride out with Forscan connected, what should I be monitoring, and can it record the "activities" so I can look at them back at home?

[metalworker0]

Frst you have to populate forscan with the items you want to observe - then put it into "live data" mode - plenty of youtube videos on how to do that.

Then you are looking at the EGR values in percent ... "commanded" is what the system is asking it to do
"Actual"is what it's doing.
You are looking for the EGR being open when it should not be open.
Anything more than brisk acceleration and EGR should be closed.

You'll also be checking for leaks in the boost pipes, a common problem is a hole rubbed through, by a bolt near the alternator.

all the best.mark

[Radiofence]

Is the egr valve a genuine one or some weird cheap make ? Might be worth buying either a second
Hand genuine one to try or get an egr banking plate. With the plate you will end up with a light on the dash etc but it will eliminate exhaust gasses going into the inlet manifold and if its fine with the plate, then you know what to sundress.

[Customaniac]

Update:

Had another play with Forscan on the drive and got the following readings:

At idle (804 rpm) egrp 20%, maf 6.2 g/s
1600 rpm, egrp 30+%, maf 32 g/s
2400 rpm, egrp 49%, maf 58%

Presumably there's a problem with the "new" egr valve and either the maf sensor is shot or there's a vacuum leak??

[metalworker0]

EGR only closes on acceleration .. it opens at cruse and fixed rpm

all the best.mark