free hit
counters
Smokey black soot again.... - Engine/Ancilliaries - The Lotus Forums #ForTheOwners Jump to content


Smokey black soot again....


Splodge s4

Recommended Posts

I've had this problem ever since i've had the car, 3 and half years & 17,000 miles but its now really annoying. At motorway speeds, say 80 mph, just tickling boost i get the stumble but also quite alot of black, certailanny not blue, but black like a diesel, smoke out the exhaust. It feels like its stumbling & needs clearing out, put your foot down & it takes off fine & no smoke. After cruising for a while on the motorway the rear bumper is covered in soot.

I know Dermot had a post about the stumble & alot of us have it, I've recently had a high torque chip fitted but its not made any difference. If your motoring on A & B roads, so different speeds, it's fine.

Now over the last 3 years its been to Williams in Bristol, Esprit Engineering & I always mention it but they say everything is fine. Its not burning or losing oil & apart from the slight stumble it goes like a rocket.

Its still got the cat but a stainless steel exhaust from the cat back, K&N air filter & the high torque chip, everything else is standard.

Any ideas what it could be chaps? (oh & i dont have freescan) Thanks for your help...

Link to comment
Share on other sites


Upgrade today to remove Google ads and support TLF.
  • Replies 14
  • Created
  • Last Reply

Top Posters In This Topic

Any ideas at all? :blink: Maybe its running rich when on boost, secondary injector probs? Would freescan show what it is? Its now booked in at Interpro near Bristol for a rolling road check but not sure how familar they are with Esprits...

Link to comment
Share on other sites

Any chance of a Freescan log sending over for comparison Splodge?

email to [email protected]

Any ideas at all?  :blink:  Maybe its running rich when on boost, secondary injector probs? Would freescan show what it is? Its now booked in at Interpro near Bristol for a rolling road check but not sure how familar they are with Esprits...

<{POST_SNAPBACK}>

Link to comment
Share on other sites

Having followed you up the A46 I can definitely vouch for the clouds of black spouting astern!

It looks like carbon to me - certainly not oily at all... Perhaps you should try Optimax instead of derv!

Couldn't be that head is coked could it? Or failing that a cat that's falling apart? I think the cat bricks are light colour, but you never know.

To be honest Williams in Bristol are fooking rubbish so I wouldn't trust a word that they said!

If you want to try swapping some bits in and out of my S4 to see if it makes any difference then give me a shout.

Cheers, Ian :blink:

Ian

Link to comment
Share on other sites

  • 3 weeks later...

Put it on a rolling road yesterday at Interpro in Thornbury near Bristol. After a couple of hours checking the ignition, injectors & a load of other stuff it turns out its very rich when on boost but lean when ideling, its the fuel presure regulator.

They are looking in to an adjustable regualtor rather that the standard Lotus part & should be fitted in the next few days. Then we can see what bhp its putting out. :(

Link to comment
Share on other sites

I will be interested to know what do regarding fuel regulators. I have looked into this in some detail and have suggestions if you wish.

Further, before you blow a lot of cash have you checked if the current one is working properly, you need to check the static pressure an it rises correctly with boost. If it OK I doubt a new regulator is going to solve your problem.

Does that garage not realise that your are in closed loop mode in idle and crusing. Therefore it is using feedback loop with the O2 sensor output to adjust the fueling. If you change the fuel pressure the fuel tables will be way out initually but the ECU has an adaptive long term fuel trim memory table, it will adjust the BLM values to bring teh fueling back to the same position after a few 100 miles.

On stand alone ECUs with wideband O2 sensors it is possible to adjust all this and reprogramme the A/F as a function of load, rpm, boost etc....

I coud go on....

Dermot

Link to comment
Share on other sites

I will be interested to know what do regarding fuel regulators.  I have looked into this in some detail and have suggestions if you wish.

Further,  before you blow a lot of cash have you checked if the current one is working properly, you need to check the static pressure an it rises correctly with boost.  If it OK I doubt a new regulator is going to solve your problem. 

Does that garage not realise that your are in closed loop mode in idle and crusing.  Therefore it is using feedback loop with the O2 sensor output to adjust the fueling.  If you change the fuel pressure the fuel tables will be way out initually but the ECU has an adaptive long term fuel trim memory table, it will adjust the BLM values to bring teh fueling back to the same position after a few 100 miles.

On stand alone ECUs with wideband O2 sensors it is possible to adjust all this and reprogramme the A/F as a function of load, rpm,  boost etc....

I coud go on....

Dermot

<{POST_SNAPBACK}>

Thanks for the info Dermot, first thing I asked is have they worked on Esprits before and apparantly Williams the dealer in Bristol has used them a few times when they have probs that needs a rolling road. I assume they know about closed loop modes etc, however there bread & butter is Jap stuff, there were 3 Impretza's in with engine rebuilds & a Supra. Is the Esprit very different when it comes to fault finding?

He did mention the o2 sensor was trying to cut the fuel back but was operating at its maximum, they way i understood it was the fuel pressure regulator was faulty & allowing twice the fuel in on boost than it should, the O2 sensor was reading this & trying to trim it back but was at its maximum. Have to admit when it comes to this side of mechanics im not to good.

Do you think if we change the regulator the fault may come back after a few hundred miles? What else could it be? Thanks again for your help...

Link to comment
Share on other sites

I am afraid modern Jap cars have ECU't that are much more fancy.

I freescan log of you car would be very informative if you could arrange it. That woulod allow me to see what fuel compensation the ECU is applying and it it is out of the ordinary. Most of the time the ECU is cutting back on the base fuel tables.

I am concerned by some of the the things they are telling you.

The fuel pressure reg is a raising pressure regulator. In the Lotus workshop maunual it give the base pressure which you can measure on the port. I think it is 43 psi from memory then it raises in a 1:1 relation with boost. The fuel reg cannot let more fuel in, the injectors do that. The fuel is recirculated at this pressure.

Depending on how the dyno works, on power runs you could be in power enrich mode, under these conditions the ECU adds addition fuel as an additional chargecooling effect and to prevent knock.

Dermot

Link to comment
Share on other sites

I think x6gas has freescan & lives just down the road so ive sent a message to see if I could pop over to his one evening. Failing that i'll stop being a skin flint & buy it myself..

What causes the power enrich mode, you mentioned the ECU sensing knock so adds more fuel but I assume thats controlled by the chip? When i recently changed the chip to high torque it didnt make any difference, I was kind of hoping the 3000rpm stumble would disappear but its exactly the same.

As always, thanks for your replies Dermot.

Link to comment
Share on other sites

If you get the log done i will look at it for you.

Power enrich mode is entered by throttle position and acceleration, which is what you do on many dynos ie. WOT and hold on...

The low A/F are preprogammed to prevent knock and piston melting at high boost. I am not expecting to see knocks from you engine in your setup.

If the wastgate actuator is not set correctly this can enhance the 3000 rpm stumble. Most well setup cars running revised Whittaker codes should have almost no perceptible stumble at 2800-3000 rpm. I can look at that also in the Freescan log.

As you can see, I can't imagine why an SE/S4/S4s or GT3 owner does not have Freescan capabilities it will same you

Link to comment
Share on other sites

Just a couple points. I had a fuel pressure regulator go out on another car (supercharged 5.0 mustang) and it dumped alot of fuel into the cylinders. It doesn't seem that this is your problem, but the extra fuel in my case caused me to bend a piston rod on startup as the cylinder filled with fuel. Also, too much fuel in one of the cylinders while running could water down the oiling properties of the oil in the piston rings and cause excessive wear. Have you checked your oil for any indications of fuel being mixed in?

On another note, I had the stumble you are talking about and changed to the high torque chip too. In my case it did help with the stumble quite a bit. Every once in a while it comes back but a reset of the ECU makes it go away again.

Anyway, sounds like you are on the right track with the Freescan plan and advice from Dermot. I hope you get it figured out as I know how annoying smoke from the exhaust is (mine was from a worn turbo).

John
94 S4

Link to comment
Share on other sites

Ok, so plan of attack, get freescan. Thanks for the offer to look at it Dermot, i'll take you up on that as soon as poss.

It was discussed about the wear on the cylinders through fuel breaking down the oil, theres no evidence at all of that, I check the oil everytime I drive the car, at least once a week & its fine. The mecahnic guy did say that could happen but no signs of it. Thank god. :rolleyes:

Also when you mentioned resetting the ECU when the chip was first fitted at Esprit Engineering driving back the car was smooth & no real stumble, after about 30 miles there was a noticeable change and it came back. I have since reset the ECU but the stumble was immedeatly there. It takes about 30 miles or so for the ECU to re learn but as it didnt make a difference after trying it again I didnt think anymore of it...Could that be important?

Techspy, how often do you reset your ECU, surely not every 30 miles or so?

Link to comment
Share on other sites

No, definately not every 30 miles. If memory serves (as I havnt even seen my S4 in over a year) it would be like around 500 miles or so. This doesn't mean that every 500 miles or so. I can actually only remember doing this twice in a 9 month period. I started researching the actual cause of the stumble and a fix, but the only fix that seemed to be documented as working was drilling many small holes into one of the vacuum hoses related to the wastegate (again this is from memory from about a year and a half ago). It is hard for me to comprehend that this problem hasn't been fixed via ecu code by now.

John
94 S4

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



Upgrade today to remove Google ads and support TLF.


×
×
  • Create New...