MR2 Roadster Owners Club

The Workshop => Performance Related => Topic started by: WillsSayers on October 7, 2008, 22:46

Title: MAF sensor need replacing?
Post by: WillsSayers on October 7, 2008, 22:46
Hey al,

I've got a flat spot in my rev range at about 4.5k - 5k revs, which is most noticeable in 2nd and 3rd. Do you think this could be sorted by getting the MAF sensor replaced, or even just cleaned? It's an 8 year old car with 74k on the clock.

-Wills
Title: Re: MAF sensor need replacing?
Post by: Wabbitkilla on October 7, 2008, 22:49
Take it out, clean it, reset the ecu, put it back in and try it.

Worth a try, and miles cheaper than buying a new MAF!
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 7, 2008, 22:56
Baring in mind I'm quite a car noob, what's involved in removing it? I've been told to spray it with Isopropyl Alcohol spray and then grease the connectors with dielectric grease - does this sound about right?

How do you reset the ecu? Is that a battery out/in job?
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 7, 2008, 23:04
Found a guide here; assuming this should be as straight forward as described?  s:) :) s:)

 m http://www.spydermagazine.com/2002/Marc ... _clean.htm (http://www.spydermagazine.com/2002/March/maf_clean/maf_clean.htm) m
Title: Re: MAF sensor need replacing?
Post by: kentsmudger on October 7, 2008, 23:11
Dead easy, just follow the instructions you have there - If you disconnect the battery before you start and put it back when you're done (half an hour is enough), you will get an ECU reset too.

Enjoy  s:D :D s:D
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 7, 2008, 23:14
Wicked, I'll see if I can pick up the required stuff and give it a go tomorrow or something then. Would love to get rid of the flat spot!
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 8, 2008, 17:01
Quick question looking at this picture:
(http://www.spydermagazine.com/2002/March/maf_clean/maf_wires.jpg)

Are these actually inside the removable part of the sensor, or are they inside the air intake pipe?

Cancel that, just spotted them!
Title: Re: MAF sensor need replacing?
Post by: SimonC_Here on October 8, 2008, 17:06
Don't break or even touch them!

Spray from a distance!

Simon
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 8, 2008, 18:10
Oh ****. They both snapped, but I thought I'd try it anyway. It was fine for a few seconds, then the car burst in to flames and BLEW UP!!!

Nah, it's worked a treat! The flat spot has completely gone and the torques have returned  s:D :D s:D  I am one happy '2 owner!
Title: Re: MAF sensor need replacing?
Post by: Wabbitkilla on October 8, 2008, 18:22
YaY   s:bounce: :bounce: s:bounce:  

Good work well done, working on these cars is a matter of confidence.
There's so much info available both here and Spyderchat, and the car itself is actually pretty easy to work on.   s:wink: :wink: s:wink:
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 8, 2008, 18:28
That's very true. This is actually the first car I've decided to work on myself though, so I'd much rather have my hand held by using this forum first, y'knarr? :]
Title: Re: MAF sensor need replacing?
Post by: heathstimpson on October 9, 2008, 12:59
Quote from: "SimonC_Here"Don't break or even touch them!

Spray from a distance!

Simon
Some carefully use a cotton bud to wipe over  s:? :? s:?
Title: Re: MAF sensor need replacing?
Post by: StuM on October 13, 2008, 00:16
Cleaned my MAF and reset the ECU today - first reset since gutting the precats.  Car now running really well - throttle response and general 'pick up' much better.  If only I'd realised early how quick and easy a MAF clean was!

Cheers Will for reminding me to do this!

Stu
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 13, 2008, 11:14
Does gutting the pre-cats actually offer a performance increase, or is it soley to reduce the chance of engine failure?
Title: Re: MAF sensor need replacing?
Post by: StuM on October 13, 2008, 12:01
Quote from: "WillsSayers"Does gutting the pre-cats actually offer a performance increase, or is it soley to reduce the chance of engine failure?

Open to debate.  There must be an increase in airflow into the engine with all the pre-cat material removed, so I'd say a small increase.  It certainly sounds a bit louder than it did before.

Stu
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 13, 2008, 12:13
Hmmm, perhaps I should get my gutted... Bit of a chore though as I'm awful with this sort of thing by myself!

Am I right in saying it'll fail MOT unless it's been warmed up for a few minutes first?
Title: Re: MAF sensor need replacing?
Post by: edward.carter on October 13, 2008, 12:35
get a local garage to do it. And mot is not a problem, i dont know of a single person that has failed mot due to precat removal. (they are for the american ulev test) So not applicible here.
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 13, 2008, 13:26
I thought it'd be good to do it myself as I quite fancy learning a bit more about mechanical stuff ;]
Title: Re: MAF sensor need replacing?
Post by: edward.carter on October 13, 2008, 13:58
in principle its a simple job, few nuts and bolts take manifold off, drill out precats, spray some water through to clean and bolt back on.
But!
after seeing the game markiii had at the precat gut meet (mine being one of the worst with stuck bolts and the heads sheering clean off, id never attempt it myself unless the car was about a week old and the bolts hadnt rusted lol.
Also his pit was a big help made getting to the bottom half of it much easier.
Many people have done it themselves, and i wish you luck if you do, just a little warning  s:) :) s:)
Title: Re: MAF sensor need replacing?
Post by: ad_car_08 on October 17, 2008, 17:46
Quote from: "kentsmudger"Dead easy, just follow the instructions you have there - If you disconnect the battery before you start and put it back when you're done (half an hour is enough), you will get an ECU reset too.

Enjoy  s:D :D s:D

So 15mins isn't long enough?

What can be experienced after the ecu is reset? does the engine start really lumpy and revs shoot up and down?
Title: Re: MAF sensor need replacing?
Post by: spit on October 17, 2008, 19:23
Quote from: "ad_car_08"So 15mins isn't long enough?
No, 15 mins should be plenty long enough.

Quote from: "ad_car_08"What can be experienced after the ecu is reset?
Cleared CELightand the ECU starts learning its trim with a (hopefully) more accurate MAF reading

Quote from: "ad_car_08"does the engine start really lumpy and revs shoot up and down?
No. What you're describing there sounds to me very much like a sticking IAC valve - characterised by a lumpy cold start idle and hunting revs/running a rich and fast idle when warm. If that's what you're experiencing, let me know - gonna take some pics of a dismantle, clean-up and reinstall soon - worth knowing about 'cos a replacement part is over 200 quid   s:shock: :shock: s:shock:
Title: Re: MAF sensor need replacing?
Post by: northernalex on October 18, 2008, 00:52
Will, pop to S-Cars.. they will do the gutting for you.

Alex
Title: Re: MAF sensor need replacing?
Post by: WillsSayers on October 18, 2008, 08:59
How much for, fella?
Title: Re: MAF sensor need replacing?
Post by: northernalex on October 18, 2008, 10:39
Quote from: "WillsSayers"How much for, fella?

Not much, give them a call I know they have done it before... id bet circa 50-100 quid - 01388811855

Alex
Title: Re: MAF sensor need replacing?
Post by: ad_car_08 on October 18, 2008, 13:05
Quote from: "ad_car_08"does the engine start really lumpy and revs shoot up and down?
No. What you're describing there sounds to me very much like a sticking IAC valve - characterised by a lumpy cold start idle and hunting revs/running a rich and fast idle when warm. If that's what you're experiencing, let me know - gonna take some pics of a dismantle, clean-up and reinstall soon - worth knowing about 'cos a replacement part is over 200 quid   s:shock: :shock: s:shock: [/quote]

Ohhhhh no no no!!! When I reconnected the negative terminal onto my battery and turned the key, it started first time and performance seems unchanged as if I hadn't done anything to the car at all!? I wasn't expecting any dramatic performance differences, but I cleaned quite alot of grime off the sensor so I thought I'd notice the difference?

Seems I'll have to invest in a markiii to set sale on the quest for performance differences!!  s:lol: :lol: s:lol:
Title: Re: MAF sensor need replacing?
Post by: spit on October 18, 2008, 14:14
Sorry bud, I was only answering your question! Not sure why you asked if you didn't get those symptoms  s:? :? s:?  

I'll put the camera away then...  s:lol: :lol: s:lol:
Title: Re: MAF sensor need replacing?
Post by: ad_car_08 on October 18, 2008, 22:22
Quote from: "spit"Sorry bud, I was only answering your question! Not sure why you asked if you didn't get those symptoms  s:? :? s:?  

I'll put the camera away then...  s:lol: :lol: s:lol:

I was asking because i didn't think i'd reset the ecu, so i was asking for symptoms which show an ecu reset  s:D :D s:D