Power Loss with Diesels: Guide - Alfa Romeo Forum
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Power Loss with Diesels: Guide

Just writing this guide to help people who have any power loss, or feeling of limp mode with their JTDM, most of the issues between the 1.9 and 2.4 seem to have similar causes and solutions.

When people suggest you start with the below list, they are not being difficult, but the majority of power loss issues people have are covered below. They are simple to check, and to go through , once they have looked at you can hopefully remove them as an issue before you start looking at 'more serious issues' that require more work, better DIY skills and tools.

One of the most common complaints to power loss with these engines is at low revs, with drivers complaining that there is no power, with the car picking up again at around 2-2,500rpm. Firstly, if you can get any fault codes read, will often help you determine the issue if it is not the usual suspects.
The most common causes for this are:

EGR blocked:

Probably THE most common issue (90% plus), especially after 40,000miles (seems more cases are also raised during cold snaps!), normally diagnosed by a lack power lower down that seems to recover around 2,000rpm, when severe can stop the car starting, or in the early stages as a cough or stutter around 2,500rpm.

Can be easy and cheap to fix (and personally think cleaning it is a great preventative measure anyhow). If you want to determine if this is an issue, cut a piece of drinks can and place it between the EGR and inlet pipe (loosen the two bolts on top of the EGR, and slide it in underneath) (the guide below should make it clear where).
https://www.flickr.com/photos/28496053@N04/8359349986/

I think it is probably worth skipping this step and cleaning it anyway (see below).

If this is an issue, then first step is to try and give it a good clean, ( guide below). You often don't need to do the whole drilling thing, but just give the rest of it a clean. If the solenoid is still stuck, then you can pick up a new EGR for as little as £80.
http://www.alfaowner.com/Forum/alfa-...tructions.html (note on the 159, the engine cover just pulls off, no nuts or bolts involved).
Or watch this video, shows how easy it is.

To help prevent this issue in future, you should obviously clean it, then you can either blank off your EGR (which, without a new map will introduce a fault code), or restrict it with a restrictor plate (this is an official Fiat Mod, and can be purchased from the dealer, indepdent, or elsewhere),

MAP Sensor

Another sensor that is prone to getting clogged up, doesn't seem to cause major problems though, one hex bolt to remove and clean with carb cleaner, my car revved noticeably smoother after cleaning, it's just to the left of the EGR (there are some images lower on this pages courtesy of Alfadisiac):
http://www.alfaowner.com/Forum/alfa-...ere-is-it.html
Youtube video showing location and cleaning of the MAP

DPF Blocked:

Another common one (though not always just at low rpm, often lack of power throughout the rev range), if your car is often used for city driving it is more likely. DPF blockage causes increased back pressure on the engine. Take it for an italian tune up on the motorway (30-40miles, at >2,500rpm), a dealer can do a forced regen, you can also get a bottle of WYnns DPF cleaner that allows the DPF to burn off soot at a lower temperature. Some drivers have been known to drill into their DPF, jet wash them, or remove them (with a remap(£300+) or a special dongle (£30) ).

Boost Sensor:

If your turbo is not picking up, then you could have a leak in some of the boost pipes or the boost sensor could be dirty. This is a small black box on the front right (as you look at it) of the slam panel. Sometimes the pipes crack, or the sensor/ valve just gets dirty.
http://www.alfaowner.com/Forum/alfa-...re-at-all.html.
Cleaning the vacuum boost solenoid:
https://www.flickr.com/photos/284960...ream/lightbox/
Check the pipes for a hissing noise, or a piece of toilet paper on a stick, especially if a mate can rev the engine).

MAF sensor:

Easy to diagnose, tends to show up first above 2,000rpm (across the range when it's fully dead), simply unplug the sensor, and should give 'normal' performance. Sometimes associated with a bit of smoke. You may be able to get away with just giving the sensor a bit of a clean (spray cleaner, avoid touching it). A faulty MAF can be linked to a failed EGR, as it can send the EGR crazy as it tries to compensate in conjunction with the MAP. It's a plug attached to a large black pipe onthe front right of the engine (left side when looking from the front).
Also only tends to be an issue when the car is warm, as the engine uses a default map up until it reaches operating temperature.

Injector Loom

There is an issue with the plugs on the injector looms corroding, this is especially true on engines built before 07 (when the plug was changed). On the 1.9 this seems to be injector 3, and on the 2.4 injector 1 (but not limited to those!). This causes misfires and poor idling, often will bring up an error code. You might want to play round and check the connections.
There is a repair kit for it available from Vauxhall and autolusso etc; Partnumber 93189918 / catalogue number 62 86 769
http://www.alfaowner.com/Forum/alfa-...ctor-wire.html
For the 2.4 there is a software update, probably best to get that done first!

Swirl Valves / Intake manifold:

Again these can cause a loss of power low down (mainly due to EGR which soots them up). On older engines (with a metal manifold), you can see relatively clearly if one is sticking. Not so easy on the newer 'plastic' (black) manifold. A short term fix is to spray some carb cleaner in through the intake pipe which may, or may not loosen the deposits. This thread gives a little more info:
http://www.alfaowner.com/Forum/alfa-...rl-valves.html

Battery Earth Lead

The strap that connects the battery to the ground (chassis) often comes lose or corrodes, this will cause poor idle, and often a few fault lights. The lead goes from the negative and connects to the chassis directly below the batter (often need to take the battery off to tighten). In an emergency, or to check, you can try connecting the battery to the engine/ chassis with any old jump lead.

Glow Plugs

You may well get this display on your dashboard, unless it's -5c or worse your car should be ok, only issue may be the car taking longer to start than normal (it's not normally associated with a loss of power, even when cold). If you get this, it's normally one of four things: Failed Glow Plug (should read about 1 Ohm, also connect the plug across the battery, the tip only should glow after a second or two), Fuse blown (a 60a 'Midi' fuse, it's F73 and is the yellow one on top of the battery), or the glow plug control unit on the bulkhead. More details on all this:
http://www.alfaowner.com/Forum/alfa-...available.html

Throttle Body/ Manifold

Not usually an 'overnight issue', but as the car ages, your "throttle body" and manifold is likely to start getting gummed up with a mixture of oil and soot (from the EGR and the oil Breather). This is going to start blocking off and affecting the butterfly valve in the throttle body and restricting flow through the manifold (and increasing the pressure on the swirl flaps which may break).
Cleaning the manifold properly is a difficult job, best done when you get the timing belt done (as it has to come off to access the manifold). However the throttle body can be done yourself (link below). In terms of the manifold, to help things along, spray some intake cleaner or EGR cleaner into the manifold (best access is through the throttle body, EGR or MAP ports), this will help to soften and loosen some of the gunk (mine gave off a lot of dark grey smoke after doing this!!). Blanking the EGR will also help reduce the likelihood of this happening!

http://www.alfaowner.com/Forum/alfa-...clean-out.html (How To: 2.4 JTDm throttle body & EGR clean-out) (note the 1.9 is near identical, but with a bit more space!)
lakson, TimBud, HTA and 2 others like this.

159 1.9JTDM Ti and Giulietta 2.0 Veloce
ex: Punto 55s, Golf Mk5 1.4FSi, A3 (8P) Sportback 2.0TDi SE, A4 (B8) 2.0TDI S-Line, 306 HDI Meridian

Last edited by giblets46; 31-01-17 at 15:13.
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If your DPF is totally blocked then the car may stall and/or loose all power (it won't pull up a hill).

If you cannot remove and clean the DPF then I think that another solution is to drop the DPF down thus disconnecting it and the rest of the exhaust and drive to a dealer otherwise you may need a recovery lorry.
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Slightly different, but.....

An odd fault I had with my 2.4 Brera was an appearance of "check engine" when blatting along an A road, but with no obvious immediate signs of distress, but I quickly noticed that the turbo gauge was showing no boost at all.

Pulling away from the next roundabout there was certainly no boost and seemingly only a minuscule amount of power (foot flat to the floor in any lower gear to get any acceleration), but I limped it to a lay-by a few yards on. By this time the warning messages were coming thick and fast (no ABS, VDC, no hill-holder, etc etc.)

Called the AA, who plugged in the diagnostics, and traced the problem to the wiring loom that runs in front of the battery tray, the edge of which had worn through the binding and the insulation on one of the wires which had blown a fuse knocking out the turbo and all the other systems. A new fuse and a good winding of electrician's tape on the loom plus a couple of restarts and everything was back to normal, lots of boost and no warning messages.

I've not seen anyone else report the same problem(s), but worth bearing in mind perhaps.....

Tirreni

Alfa History: 145 1.7, GTV2.0, GTV 3.0 V6, Brera 2.4 JTDm
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Very nice summary!
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Good shout Giblets
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Map sensor is an easy job to remove and clean (one bolt) and in my experience gives excellent results.
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Great stuff. I now have a list to work too! Haha
1st up is the MAP sensor....
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were is the MAP sensor situated on the 2.4
 
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I cleaned the MAP once and made no difference. Supose it wasn´t clogged or anything like that. The EGR tough made me feel a substantial difference, mainly on traffic pull aways, and wintery mornings were a lot easier for the car!
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Hi Giblets

Your advice and fixitsan has been really helpful in fixing my 1.9jtdm issues. However I need your advice again. After semi drilling dpf, adding a new EGR, cleaning the MAP, my car still stumbled at light throttle, I disconnected the MAF and viola! She ran like a new one. So i ordered a new MAF sensor and fitted recently as I didnt like the EML light being on all the time. However with the new MAF it still has an tendency to stumble on light throttle settings, without it connected runs great. The new MAF certainly improved the stumble but did not elimnate it completely.

Would resetting the ECU be helpful/necessary? It is obviously something related to MAF and signal of same.

Thanks again,.
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Resetting will help. It will normally take a few drives before it learns the new MAF ( without a reset) Also give the MAP a quick clean if it has had EGR gunk flowing over it.
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Cleaned my MAP sensor just now. It was minging! Hate to see the inside of my manifold! (Next job I think)
Before
ImageUploadedByTapatalk1368905837.263885.jpg
After
ImageUploadedByTapatalk1368905859.706583.jpg

Don't want to reset the ECU as it ran awful last time I did this so I will let it set its self up again over a few drives. Hope this makes a noticeable difference!
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MAP & MAF sensors should not need to be reset or re-learn as they supply readings for the ECU to interpret in real time...
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Quote:
Originally Posted by Alfa.Romeo View Post
MAP & MAF sensors should not need to be reset or re-learn as they supply readings for the ECU to interpret in real time...
Good point. Makes sense thinking about it!
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Thanks Giblets

Sounds like some of the jury is out on the reset the ecu deal. I did clean the MAP sensor some time ago which didn't improve anything, so far the biggest change was disconnecting the MAF as it ran perfectly, installing a new one (MAF) improved running but still that stumble keeps rearing its head on light throttle. I'll keep investigating.

Regards
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I experienced some power loss low down with severe "turbo lag". No fault codes could be found. Fitted a full blanking plate to the EGR valve and that solved the problem and the car is pulling better than ever!

I expected a warning light to come on, but up until now (about 100km and at least 6 starts) nothing yet. Does it take some time for a warning or fault code to show up?
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If you have the 8v engine (120bhp) I don't think you will get an error for blanking of the EGR. I'm not sure about the 20v (200bhp) engine though.
16v (150) and 20v (210) will get the error after a couple of starts, mine was every 3-4 starts before having to plug FES in...
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I have the 200bhp 20v version.
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Quote:
Originally Posted by Alfa.Romeo View Post
MAP & MAF sensors should not need to be reset or re-learn as they supply readings for the ECU to interpret in real time...
What about EGR?

I removed, cleaned and fitted a partial blanking plate today. Seems to pull better on throttle, but at idle it keeps revving it's self slightly. Do you think the ECU will need to learn the new Air, fuel, exhaust gas combination?
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I Know it's kind of covered under swirl valves, the air intake manifold is also a big culprit of power issues.
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Defiantly needs to be a sticky
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Can anyone point me to the position of the MAF?

Thanks

Update: all good located it below the air filter.

Last edited by Soldiiier; 09-02-14 at 06:11.
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so my car (1.9 jtdm) has next to no power, i have had a search for several things about loss of power and boost. They all seem to point back to this thread so i will post on end here.

So yesterday i'm sat at traffic lights, car made a slight judder (music was on at the time so couldn't here properly but there was a definite rattle when it first happened so turned radio off to listen). When i went to pull away the car would hardly move, next to no boost but it does climb a little if you keep your foot in it.

Managed to limp the car back home for an investigation. I spent 5 hours looking through the forum and going back out and fiddling. I have removed the EGR, it all moves freely and not that dirty and the solenoid is free and moves about using solenoid test on MES - so stuck it back on, no change.

Removed map sensor which was quite dirty, replaced and tried again, no change.

Checked the two lines to the boost solenoid , both free and clear and no splits or cracks, again you can hear clicking and stuff happening if you actuate it from MES. Can this sensor get clogged? Anyway to clean it or is it just replace?

Tried disconnecting the maf while running, no change.

I would point out at this point there has been no warning lights or eml come on (apart from when i disconnected the maf obviously, but clear that code and nothing comes back)

Now by this point i'm totally bemused and start thinking what else could stop a turbo spooling properly and all i could think of was blocked exhaust. So despite the car telling MES the dpf clogging is normal right now i did a forced regen. As soon as i started the regen the car revved upto 3.5k as it should for the regen, it wasn't slow at all - just as normal. (i have attached a screenshot of near the end of the regen just incase someone can see anything unusual - first time i have done one).

So after the regen, i turned car off for 15seconds like MES says to do, turned it back and and checked for codes - nothing returned. So gingerly i creeped off the drive and drove round the block. Everything seemed back to normal. But 7 miles later it was the same - it was a further 23miles to my destination and back again during which it generally won't go over 3k but sometimes the boost would come in at 3k and the car would take off only for it to stop revving past 3k moments later, after changing up a gear for example.

So now i'm well bemused as to what the problem is and how i can possibly narrow it down with the limited tools and stuff i have here (moved house but i'm at my old house 200 miles away with hardly anything to hand). Do i presume that the dpf is clogged or what? I can't find any thread at all referring to these symptoms but without an eml

edit:Just to add, car sounds and idles fine - but i would say it seems to miss a tiny bit when it starts and doesn't start as well as it did before the issue.
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Last edited by Blu73; 09-02-14 at 09:55.
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I'm having the exact issue that you described above minus the shudder

I'll be interested to see what u find blu73
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Right I have just gone and started car, very lumpy idle this morning. Foot to floor, took an age for the revs to climb but once it got up to 3k ish turbo spooled up and it then revved a little more freely but nothing near how it should, still would be hard to get going with it like that. Still no warning lights etc.

So thought i would have a look at some of the values for some stuff with engine running and this is what i found. Everything appears at a glance to be fine however, the 'throttle angle' never changes - stuck fast on 4.997. I assume this is the angle of the butterfly in the TB??

Other strange results are 'EGR' stuck fast on 3.998, so i presume despite it all appearing to work and making the right noises etc its not actually moving - having had it off to clean y'day i can only assume the gearing inside is messed up.

Other thing i found is if i go to the actuator tab on MES where you can make all the solenoids etc move, everything makes a click or whatnot but the test always fails on 'fuel pressure reg', high pressure one completes though. And the DRV value on my log (I think this is the fpr value?) is returning 0 under all conditions.

So i'm thinking these 3 things are probably my problem, i can see the egr being faulty making throttle body coke up and stop working but this fpr thing can't be related in my head or am i missing something?

Still bemused how the car just revved up fine when i told it to do a regen y'day though if the TB butterfly is jammed nearly shut. I guess once i get the thing to rev up the first time the boost could push it open slightly so it then revs a bit better???
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