Disconnecting MAF - Result on Engine?

Evening all!

Right, TD4 2005 - 90k ish.

After some performance problems, I disconnected the MAF and got major improvements with low end power, The usual, so i left it disconnected. i got a new one from island 4x4 (Circa £90) turned out to be Non Bosch, so tried it anyway when I did a service and Clutch & Flywheel change. Turned out to be naff, so left it disconnected anyway whilst I saved up for a Bosch one.
In the mean time, I was towing about 4 weeks ago and had a major failure of the bottom end bearing, car kaput then wouldnt start again! (Symptoms - rattle over 2000 revs for about 10 miles then a big graunch whilst engine braking - Oil from front oil seal, no power and finally just as I arrived at my destination a mile or so down the road.....death!)

So 3 weeks on, I have a new (ish) engine fitted to the car (all ancilliaries from the old engine). It sounds alot better than the old one with less clatter, however. The hessitation still remained on the engine when I got it back, I asked the guys if they ftted my old maf back on the vehicle, and they said they did (So thats the new duff one!) I went to Euro car Parts today and got a New Bosch MAF and fitted it, started up it idles fine, however when you rev it it jumps up to 2000 revs in about 3 stages and jums about. I took it for a drive and left a random trail of smoke behind me whilst accelerating with low revs, however the smoke dissapeared as soon as the turbo kicked in. If I drove the car hard, it would not smoke!

Bosch MAF now disconnected again and car runs fine.

Question is:

Did my last engine die in a catastrophic Ditch due to the MAF being disconnected? Overfuelling?

If you disconnect the MAF does the ECU ignore other sensors?

Is it likely that the last 2 mafs (1 x Bosch 1 x 4x4) are kaput or is it some other gremlin or component/sensor to blame.

I know there have been other MAF posts etc, but few with a doomed engine possibly as a result.

Thoughts or abuse Welcome
:crazy_driver:
Gareth

Update - Sorted!

Spent the morning on the Car, and completed the following which has solved the problem. (For now eh!)

Disconnected battery!

Removed EGR & cleaned with panel wipe (5 ltr drum for £5.00)
Removed Intercooler hoses, checked for cracks etc and cleaned.
Removed and Cleaned Inlet Temp Sensor
Removed Manifold and cleaned in a bath of panel wipe with the babies Bottle brush to clean it through (wife not impressed!!! The Tommee Tippee ones are great!)
With the manifold off - Removed MAP sensor from the manifold which was thick with crud and the orifice was totally blocked in the scavange space - all fully cleaned.

All put back together, MAF refitted, started up and left to warm up for 10 mins then taken for a Italian Tune up!

What a difference, a little smoke on hard acceleration from standstill (probably the remainder of the manifold deposits), but top end great with no smoke at all.

I am now unsure about the MAF theory of so many being duff, at the end of the day, if the MAF is disconncted there are several other sensors that are taken out of play, did the MAP (Manifold Aibsolute Pressure) sensor blockage cause the smoking and poor performance under 2K?

(MAP Sensor care of Euro Car Parts)
The MAP sensor or the Manifold Absolute Pressure sensor is a sensor that measures the changes in vacuum pressure and sends a signal to the ECU. The ECU then calculates the engine load and calculates the fuel and timing.)

There is more air able to get through the manifold now!

Or was it the EGR that was cleaned about 8k ago and again now? who knows

I also took a fine toothed saw to the Air filter cover so I can disconnect my MAF or remove it as the bolts at the back of the cover are a B*****D to get back in for some reason! Quite a good mod, that does not in any way interfere with anything else but saves time when Diagnosing MAF issues!

1/4 inch socket sets are the way of the future.

Hope this helps some other guys with similar problems.

Gareth

Off to have a wash in Petrol!:flame2:

Where is the MAP Sensor?

MAP sensor is on the left hand side of the Manifold when you look at it from the front of the car. It has the usual spring loaded 3 pin plug on it.

That square black thing just under the "H" on attachment below, It is bolted on with a 10mm

G

generally you cant see it because of the engine cover, and it unplugs downwards towards the sump.

I would think that as the map sensor isn't used much below 2k rpm that the issue was somewhere else, maybe a wiring/connection fault which has been corrected with the other work.

There's no reason for a faulty maf or maf disconnection to have damaged your original engine.

cheers chaser,

was just a thought incase iI had to do it again. couldnt afford another £1600 quid!

Now got a clunk when i come on and off the power, coming from the front off side? not driveshafts by the sound of it.

G

an engine mount or steady bracket been left loose??.....

The garage plums left my bottom tray loose by about 20 turns on both front Bolts!!! I thought it was that, but no, its still happening!

Sounds like the timing chain a bit loose and hitting off the side of the timing cover when i put load sharply (Clutch out quickly) on the engine, or, acelerate then ease off quickly then re accelerate again - that movement would produce 3 loud taps.

If you got a bike chain and wipped it on a engine lump, thats what it sounds like, not rattly, just one click / tap?

Could it be the chain tensioner?

AGW said:

The garage plums left my bottom tray loose by about 20 turns on both front Bolts!!! I thought it was that, but no, its still happening!

Sounds like the timing chain a bit loose and hitting off the side of the timing cover when i put load sharply (Clutch out quickly) on the engine, or, acelerate then ease off quickly then re accelerate again - that movement would produce 3 loud taps.

If you got a bike chain and wipped it on a engine lump, thats what it sounds like, not rattly, just one click / tap?

Could it be the chain tensioner?

Click to expand...

Nah, sounds like the engine moving in the engine bay. check exhaust and all engine mounts etc. anything close to the bulkhead or chassis that could contact when engine rocks.....

Can replicate it with the wife in the car, handbrake on as tight as i can possibly get it (thats tight), the into 1st clutch out quickly, then into reverse, clutch out quick anon anon. Only does it once each gear change though. Havent got the balls to lie under the car with the wife at the wheel ragging the clutch about, but will try some more ideas over the next few days. Engine mounts or stabiliser bar is a possibility. what would click in that, not done one before - is it an easy job or engine out?

Had a similar clonk on taking up and coming off drive, twas the lower stabilizer bar. £50 odd quid and a hour or so to replace.. That is on a 2002 TD4.

Oh and I confirmed it by lying under car with lower tray removed and grabbing hold of engine and shaking it. Could hear and feel clonk in the bushes in this arm!!

Thanks for all of your input. I solved the problem today. It was the engine mount, only about 3/4 of a turn to nip it up and that solved it. Its the Oil damped mount with the vertical bolt (cant remember the technical name!) However it is running good as gold now......What am I saying.........Off to hug some wood.

A Happy Owner Once Again (for now)!