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buzz271432

2005 Cabrio Fuel Efficiency Dropping Fast

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Hi Peeps!

 

It has been a while (Bibit II has been a workhorse >120,000KM since I purchased her in 2017!).

 

I let her rest for the winter (couldn't generate enough heat  with the soft top) but since I have had her out (late Feb)… my fuel efficiency keeps on dropping??? Yesterday I bottomed out at 6.0/L per 100KM!!! 

 

She never hit the same performance as the orginal Bibit (3.7/100KM) but was always holding steady at 4 to 4.5 ltr. We are now over 250,000 on the diesel so maybe that is the problem; I do notice a drop in acceleration and holding my speed on hills and/or strong headwinds but... the fuel efficiency dropping that fast suggests, atleast to me, that something else is going on.

 

Just completing my Oil change and sevice and was checking battery terminals when I noticed that when I crank the motor... my Battery ground sparks (the connection to the Frame). Never happened before (or I never noticed it) wondering if something else is going on...

 

Other than this new annoyance and the bumpy ride in pothole season... zero complaints and a very satisfied "old Smart owner" :thumbsup_anim:

 

Cheers!

 

Bob

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not saying that this is your only problem, but a bad ground can definitely affect your mileage. once the ground is fixed look at your exhaust when you first fire up cold. looking for raw fuel. whitish smoke and you can smell it. bad nozzle will cause this. if exhaust clean when cold, look at induction system. intercooler/turbo. check boost. a place to start

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Thanks SLipperyslope… she starts nice; no white smoke or bad smell. Recently she has been kicking into "limp mode" when driving off in the morning (only in the mornings and only occasionally). I rest the throttle body (learned it on evolution.co.uk) and... Bob's your uncle.

 

Based on Mileage beginning to think it might be time for an engine overhaul... not about to invest that kind of money, she has done me well these last 2 years. Hoping it is a minor issue. I will focus on the ground and see what happens.

 

Cheers!

 

Bob

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If it's nozzle related contact Mender as he has the contact for them. It made a world of difference for my old beater!  Not cheap but far far less than rebuilt injectors. I think it's a third of the cost if memory is correct. Just remove an injector and take nozzle off and squirt carb cleaner through it and see what the spray patter is like..I bet it's clogged and worn out. I also sonic cleaned the body of the injectors but kept the very top out of cleaner, but the rest went in and stayed there for a while.  Like I said before outstanding results.

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I think I read here recently a dirty egr can hurt mileage and also put car into limp mode.  A hole in the intercooler or rubber hose to intake is a common problem as well.  I agree it is probably not worth the money to do a rebuild unless you have the ability to do it yourself.  I know a well respected member in London that has acquired a couple of low mileage diesels in the last couple of weeks if you decide on another.  If you figure it out please let us know.

 

Nigel

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if it starts cold and is clean, probably compression is still good. low compression will result in poor ignition when cold, and you will have smoke. I would be looking for low boost ie: intercooler leak, blocked egr, air filter, turbo on its way out?   what kind of codes is it throwing?

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Try an “Italian tune-up.”

 

  1. Fill up with fresh premium diesel from a high-traffic filling station
  2. Add fuel conditioner
  3. Drive the snot out of it for an hour, including highway runs where you stay in 5th gear to keep the RPM up

i used to do this about once a month in my old cdi, and it ran like a top, and hardly ever had issues. I consistently got sub-4.1 L/100 km on my tanks. 

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Thanks Darren... I already run it daily 70 mins plus to work and back. 90% of my commute is highway but... I will add some diesel fuel conditioner on my next tank and give the "Italian Tune-Up" a try!!

 

To Slipperyslope… I change my air filter every 2nd or 3rd oil change (done monthly due to my mileage). I changed it yesterday and will see if that helps. No code reader available:-(.

 

As for EGR...I have read up Tolsen's instructions but "that tool" has me perplexed so I am hesitant to try to tackle that job . I checked Evilution for instructions but nothing on 450.

 

If no improvement I might just take it in to my local Smart mechanic to have a look. Intercooler, turbo and/or leak might be the root cause... my last Smart's (2006) Turbo died around 230,000... not sure what life expectancy is but I have gotten a great run for my money on this 05 Cabriolet. Not about to invest too much more money or time into her.

 

Thanks for all the suggestions! I will keep you posted over the next little while (she still runs other than poor fule efficiency... she runs quite nicely!).

 

Cheers!

 

 

Bob

 

 

 

 

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So... CT had the Innova 3100 OBDII Scanner on sale and I decided to splurge.

 

P0238: Turbo/Sensor Charger Boost Sensor A Circuit High

Calc Load 96.5%

ECT 156 F

MAP: 66 (inHg)

Eng RPM: 2714

Veh Speed 51 (MPH)

 

What kind of sorcery is this. LOL!

 

Any suggestions?

 

I have been adding Power Service Diesel Kleen & Cetane Boost since last Sunday (3 tanks) and it has made an improvement in both acceleration and my fuels consumption went back to about 5.2L/100Km on average but … Bibit still ain't feelin right.

 

What am I lookin at at peeps? Suggestions?

 

Cheers!

 

Bob

 

 

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Gotta love this site. I searched P0238 onCLubsmart... I guess I'm takin off the ass end of Bibit this weekend... keep you posted!

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What about inter cooler rub through...?  Simple fix with JBWeld and cheap, just a load of time getting it out and prepped for the fix.  Just some cleaner and a tube of JBWeld 5 minute epoxy the soft stuff not the bar. OR a rub in the top hose where the wiring sits on rubber hose...?

I have one JBWelded inter cooler here on bench and am running one.....no issues after a year's use.

 

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you have a problem....lol. the spec I found for max boost is 16.5 psi, your code claims 32.5 psi....

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Where did you read 32.5 psi from the data I posted slipperyslope ??

 

Update:

 

Wastegate was definitely "tight"... some penetrating oil and elbow grease and... moves much better with much less effort

Could not locate any "leaks or cracks" in the intake hose (but I'm not so sure what I'm looking for unless it is very obvious so...???).

Cleared Code P0238

 

Took Bibit for a 40Km ride on the Hwy:

- nice acceleration through all gears (been a while) but lagging in 6th. Couldn't get up over 120KMH and she was not holding speed, slowing down with even a slight incline.

- hauled ass in 5th gear tho. Hit 130KMH (4000RPM) and performed my "Italian Tune-Up"

 

I filled her up added some more Injector Cleaner and will wait and see next week. 1 Tank lasts me 2 days of driving so... should have results back fairly quick.

 

Cheers!

 

Bob

 

 

 

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The rub through on the inter cooler will be in the lower forward side I think on the left....the rub on the top hose is under where the wire loom travels over hose, you'll easily see an indent there if bad. Have you taken off EGR yet to see internal condition?  IF not i bet it'll be plugged also....jut saying....if you have the time it can all be done in a day if you stay with it......both aren't fun by any means. EGR and intercooler.  

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your scanner recorded the map (manifold air pressure) as 66 inhg (inches of mercury)..2.036 inhg= 1 psi...…….p0238 code records an over pressure...I believe on 450 it is between 16.5 and 17 psi. the high boost pressure would be consistent with high fuel consumption, but you should be making tons of horsepower, not lacking it. the map may not be recording correctly. if someone on the street told me their smart was making 33 pounds of boost, I would probably give them "that look"....I would probably be thinking about hooking up a mechanical boost guage that you can read while driving and go pull a hill. record what you are actually creating

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Update Peeps!

 

With the help from a friend (pushed throttle while I checked for leaks), discovered a leak! Clamp at "intake" hose was really loose and I could see smoke at 3000 rpm. Hose appeared fine!

 

Tightened her up, no more leak visible, took a "spirited" test drive on hwy:

- power is back (in 6th gear too)

 

I will run a few tanks to see if fuel economy has improved...

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For what it’s worth, 6th gear is useless on any kind of uphill incline. 

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This is why a remap is a good idea.  I have no problem maintaining highway speeds in 6th gear regardless if the incline (NOTE: I am not in BC where I can imagine that the inclines are more severe and selecting a lower gear might be advisable.)

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