Renault trafic IAT and throttle issue *FIXED!?!?!*

[damien4884]

2006 Renault Trafic 1.9 DCi

I seem to have become the local go to guy for these vans, got 3 in at the moment!!

Had this in last week for a quick look, wouldn't respond to throttle if starting when warm. Wiggling the MAF sensor plug made it work, didn't have the time to look into it any more and it was being used for deliveries the next day, they were quite happy to go away knowing what to wiggle and they booked in for a service and check on wiring for this Friday.

It turned up last night on back of recovery truck. No matter what you did it wouldn't rev and was idling quite low and would occasionally cut out (almost exactly like they run if you disconnect the MAF sensor). 

Fault codes were IAT low signal and MAF high signal. Live data showed 20 degrees and 758KG/HR with ignition on. Checked through the wiring from plug to ECU/earth etc all seemed fine, Cleaned earth point by ECU and Blue plug by fusebox. Checked MAF by plugging it into my van and came back at 6 degrees and 0KG/HR ignition on. Cut MAF plug off fitted on my MAF sensor and checked continuity against the terminals on their bare MAF, 2 wires were shorting against each other and one wasn't connected to sensor, inside the plug had melted. Fitted another MAF plug, starts and runs fine when cold, however i'm now back to no response from throttle when starting warm.

Chased the wires from MAF sensor all the way back to ECU and checked for damage, no issues. Peeled back insulation every 6 inches or so on each wire to see nice clean wires.

The IAT is fluctuating a lot when running, from -10 to +60 degrees, every now and again it settles down to 16-20 and will let you rev it but there are no fault codes stored.

Went through the WSM guide for IAF and MAF faults checking the wiring back to earth/ECU and all comes back good. It suggests the ECU or MAF is at fault.............

They need the van back Friday night and i'm at a bit of a loss. The MAF works fine on my van and i'm not completely convinced its the ECU at fault here, as it does work fine sometimes, usually i find the ECUs are either totally broken or fine not intermittent. Any ideas?

[damien4884]

Oh and the throttle positions are showing up as working on live data.

[valhalla]

Have you measured the ECU output reference voltage to the sensors? If there has been a lot of shorting and fusing going-on, the ECU 5v output stage might be fried. That would explain things like AIT going beserk.

Also, check that you have a good engine ground, and good sensor ground lines. Measure the ECU ground signal back to the bodywork, in case that has gone for a burton.

[damien4884]

Funny you should say that........ first thing I did was check the earths, cleaned them up (strap from end of gearbox and small ring terminal under ECU housing)

Just before shutting up shop I thought I'd give it a run for a couple of mins see if any codes came up. Checked before starting no codes, live data for MAF and IAT all good. Fired up, checked live data, MAF seems good, 57KG/Hr rising when revved. IAT started off around 6 quickly rose to 20 degrees all good for 30 seconds or so, all of a sudden the IAT started rising, hit 96 degrees before I shut it off, removed MAF and the little black pip of temp sensor has been reduced to ash......... checked voltage to it with ignition on at around 5.1v.



The little white bits in bottom of MAF are the ash that was once an IAT...........

Quickly unwrapped all the wires I'd just joined in to fit the new MAF plug and I'd done it right lol

I decided to cut off the pip and start the van again, so I could see what was happening, temp sat at what appears to be a default value of 20 degrees, checked supply voltage, 12.8v......runs and revs spot on.......

I'd already pulled all the wiring out and checked along the length earlier in the day so was nice and easy to do again, can't see anywhere along the length this voltage would be getting in other than straight from ECU..

Did finally get a code up as well. P0113 IAT circuit high input - not surprised!!!!!

[valhalla]

I think that you are going to have to monitor the voltage for the sensor supply directly at the ECU with a light-load resistor to give it something to drive against, but if you are absolutely certain there is no cross-talk from another circuit in the harness (the most logical place to start on a Renault.....) then I'm afraid your ECU is goosed.

[damien4884]

I've had all the wiring for MAF out. Checked the entire length and exposing the wires every 6 inches or so after the issues I've had with some of the others (it was a shame to pull it all apart as this ones has the nicest looking looks that I've seen on one of these vans, sat up nice and away from gear linkage, no wear or damage to the sheathing, original injector wiring, undamaged.

From looking at the old MAF plug it's had a hefty dose of 12v into the 5v supply.

I've suggested I go pick up an ECU set tomorrow, found one for sale locally. I've got a van in the corner here that almost certainly needs one (no 5v feed as it happens....) which just so happens to need the same ECU code, so if it doesn't remedy this one it should sort out the other........

[french crap fanatic]

common faults on these.
maf and egr valve together
loom issues
air box,breaks mounts and rubs through injector wires at injector.
rotten earth connections.
blocked inlet manifiold/vac pipes at manifold.
low fuel pressure can do funny things,like stop engine being reved up.
a faulty brake and clutch switch can do weired things.
oh,and like a bad earth,ive had bad positives on reno!!!usually a red colour live wire that rots and goes green powder!!!

[damien4884]

Having checked this loom end to end I wouldn't be surprised if it has been replaced at some point, it's almost like factory fresh. I'm almost certainly the first to break it open, even the injector wiring is immaculate and there's some nice alloy spacers on the air box, although the underside of box shows it's been rubbing it hasn't been rubbing on this loom.......

[damien4884]

In a kinda related note, has anyone come across the TSB field remedy 1952? Relates to no throttle response from cold for 10-15 seconds. It was suggested to the owner and they dismissed it as their issue is once warm and the van was built after the software update and injector replacement to remedy it. I got hold of it and it was worth a read, it suggests that if the fuel rail pressure doesn't hold for 3 mins after switching off engine that at least one of the injectors require replacement and to check return flow values to determine which one(s) to replace.

I've got 3 vans here at the moment and I've taken live logs of at least 4 good runners for comparison and I'd say they would all fail that test......even though they all work fine? One of them has recon injectors and that loses all pressure over the course of a minute or so.......

[Deleted]

Jan 26, 2017 21:45:57 GMT 1 damien4884 said:

In a kinda related note, has anyone come across the TSB field remedy 1952? Relates to no throttle response from cold for 10-15 seconds. It was suggested to the owner and they dismissed it as their issue is once warm and the van was built after the software update and injector replacement to remedy it. I got hold of it and it was worth a read, it suggests that if the fuel rail pressure doesn't hold for 3 mins after switching off engine that at least one of the injectors require replacement and to check return flow values to determine which one(s) to replace.

I've got 3 vans here at the moment and I've taken live logs of at least 4 good runners for comparison and I'd say they would all fail that test......even though they all work fine? One of them has recon injectors and that loses all pressure over the course of a minute or so.......

The pre 2011 van had a recall on them for common injector faults cause by the scuttle design dripping water on the injector wires causing short circuits, this also causes the injectors to rust and become hard to remove.

The other fault that seems common is the fuel pressure sensor.

[damien4884]

And so the saga continues..........

Got to the bottom of the IAT issue, Pulled the ECU plugs (only place i hadn't looked much!) removed the covers and the cable tie had worn through 2 wires exposing the core and letting them touch..........

Put it all back together, seems alright, the IAT seems a bit high, but engine seems happier at cold start. Warmed it up and the no response from throttle issue is still here!

Managed to get a nice live log with it not responding and then responding to throttle, Bare with me as my photobucket wont let me in..............

[damien4884]

So here we have it, lines 24-35 show my foot flat on the throttle and no response, i've highlighted 44 - 46 as thats when it actually responded. The fuel pressure seems to jump up a considerable amount figures are kpa and excel changes commas to dots so line 45 should read 46500KPA, of all the logs i have of these vans none of them have done that by anywhere near that amount, they usually go up to 37-38k.

I'm at a bit of a loss as to why there is no desired idle injection quantity even though it was idling, i do have live data from the van that show it working.

[damien4884]

So going back over this data above, I managed to get several logs where the same thing happens, foot on throttle and no demand for higher pressure from pump.

Now just need to work out if it's not getting a demand or not producing it and why.........

[Trevor]

With the key on engine off, what kind of readings are you getting from the your live data when u press your accelerator pedal?  

[damien4884]

Live data from throttle seems ok:



Now i have the MAF sensor and IAT working properly i now have a nice graph from earlier today:



I've had to change figures to make them in a similar range so revs are x1000rpm, rail pressure is also x1000 and accelerator position sensor 1 = 100%. I've tried to hold the revs at a certain point for a longer period to save myself from ending up with a graph all over the place.

2 things ive noticed from this graph, the revs and rail pressure have increased even though the pedal is at the same point and the fuel pressure drops lower when engine fails to respond. I've also noticed the times the engine wont rev that its idling really low..........

Customer was desperate to use it for a single drop off tomorrow so its gone away but coming back so i can investigate the fuel pressure!!

Still have a Fault code coming up at the moment, P0113 not present (A) IAT temp sensor circuit high input, every time i check it against the WSM and everything seems alright, clear it and comes back after a few starts. I have replaced both wires to IAT and its had a choice of 3 MAF's fitted over the course of the last 2 days. i'm still not sure if the bad connection in the plug led to the melting and burning of the IAT or if the 12v it seems to have got hit with came from the ECU, been getting 4.9-5.1V at sensor every time i've checked including when its not responding.  

Think i'll have a look at the fuel pressure, make sure its reading correctly and do a leak off test, if they come back OK i'll probably swap the ECU out and see what happens!