MPFI deadspot in throttle - blog **99% SOLVED**

subanator · Post by **subanator** » Sun Apr 16, 2006 1:46 am

When I start the EA82T when cold, it seems to run real rich for a few mins, black smoke from exhaust, then settles once revs drop automatically.

I am trying to find any fault codes as well, nothing so far, any clues appreciated.

Cheers,
Roger.

subanator · Post by **subanator** » Sat Apr 22, 2006 12:22 am

I have made some investigation now to the possibilities:
Its emission control related to idle. Have to trace vac line from dist to thermo device, have seem a busted port on a device that needs identifying.
Have to check fuel pressure regulator.

Engine picks up poorly from closed throttle and back again at low revs.
At idle it surges around 500-800rpm, and runs rough. Havent seen it do what I posted earlier about running rich again at cold start up.
Runs fine when warmed up and under boost.

Any clues would be appreciated.
Cheers, Roger

Gannon · Post by **Gannon** » Sat Apr 22, 2006 11:31 am

I didnt think that a 89 mpfi had a vac line to the disty, there should be no vac advance, its computer controlled. unless you have a
84-86 turbo motor in your 89 tourer

Try looking for vac leaks, around the intake piping and on vac lines as well, as vac leaks will cause bad idle.

subanator · Post by **subanator** » Tue May 02, 2006 12:29 am

Had a bit more of a poke around again, yes Suparoo you are correct, ECU controlled dist, not vac.

Have run it around during the week, seems to intermittantly to drop idle and under low revs surge. Will have an annoying flat spot before boost. Using a heap more fuel than before. Something deterioting?

Found ERG solenoid not connected - any prob here for above symptoms?
Have to check fuel pressure regulator, throttle switch, and air meter now.
Has anyone experienced any of this with these devices being faulty?

Roger

Craigus · Post by **Craigus** » Tue May 02, 2006 7:00 am

Are there any fault codes displayed by the ECU ?

subanator · Post by **subanator** » Tue May 02, 2006 11:13 pm

Craigus wrote:Are there any fault codes displayed by the ECU ?

No, had checked this a couple of times.

I have now read through the "download guides" for EA82 (Excellent job Brett!) In the Fuel Injected section 2.7, near the end is a good troubleshooting guide for throttle and expected symptom responses.
I will work through this. Firstly I will measure the fuel pressure, as the regulator is common to all my symptoms.

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Wed May 03, 2006 10:02 am

When they are very rich at idle its normally the water temp sender, they arent very well sealed from the elements and get a layer of oxidisation on the pins, pull the plug off ans scrape it away then put some WD on it and push the plug on and off a few times. The water temp sender is at the rear of the manifold and on the Drivers side.

Gannon · Post by **Gannon** » Wed May 03, 2006 6:54 pm

It could be your TPS (throttle position switch) its a potentiometer, like a volume control that tells the ecu how open your throttle is. this can cause a dead spot in the throttle.

subanator · Post by **subanator** » Wed May 03, 2006 11:34 pm

Thanks fellas, going to go over those items on the weekend.
Got a 400kpa gauge from work and will be checking the fuel pressure now too.

Post by **yarney** » Fri May 05, 2006 5:45 pm

Hi Roger i have just done a transplant from ea82 mpfi to ea82t and have the same problem using heaps of fuel idleing slow and no power untill turbo kicks in 2800 rpm haven't found anything yet.

Jan

subanator · Post by **subanator** » Mon May 22, 2006 11:49 pm

Have made some progress:
Found the main culprit for excess fuel consumption and poor running is the AFM was dirty. Cleaned out, nows runs heaps better.

Found Aux Air valve was sticking, freed up ok. Idle adjusted. Checked timing and throttle position and sensors ok. Found RHS engine breather hose dislodged from inlet duct. Changed iridium plugs from other car and gapped correctly.

The deadspot still happens at 2500-3000rpm. Most noticeable when accelerating gently. Starts to come on boost, flutters, then surges into boost progressively. Seems electrical like a lead or retarding, why at that rev range?

Also coasting to shut throttle, then reapplying it surges.

I will check the coolant switch again when hot and ERG valve, and O2 sensor etc. Not much left to check. Need a boost gauge to see what is going on also.

Any help appreciated.
Cheers, Roger

tim_81coupe · Post by **tim_81coupe** » Tue May 23, 2006 12:55 am

subanator wrote:Changed iridium plugs from other car and gapped correctly.

Aaargh! Shouldn't regap iridiums, they come factory gapped. Popping the feeler gauges in there can break the iridium tip off! 8O

subanator · Post by **subanator** » Tue May 23, 2006 9:47 pm

tim_81coupe wrote:
subanator wrote:Changed iridium plugs from other car and gapped correctly.
Aaargh! Shouldn't regap iridiums, they come factory gapped. Popping the feeler gauges in there can break the iridium tip off! 8O

REALLY....ahhrg. I never knew that. I found them to be out the box at 0.8mm and for the EA82T and MPFI it states the gap should be 1.1mm.

What should I do?? Close the gap or just leave them??

tim_81coupe · Post by **tim_81coupe** » Tue May 23, 2006 10:05 pm

Leave them now! I'd probably pull them and have a look at the tip of the centre electrode, there should be a little silver bit on the end of each one, regardless of how oiled up or carbon covered they are. If not, they're no longer Iridiums!

1.1 seems a large gap for a turbo motor! What plugs are the ones you have? I'm guessing BPR6EIX? Next time get BPR6EIX-11, they're 1.1mm already

subanator · Post by **subanator** » Tue May 23, 2006 10:14 pm

Yeah Tim, they are one of those (cant remember, but will find the old boxes in the shed - kept for reference). but are NGK's.

The 1.1mm gap is in the factory manual setting. I cant really tell any difference at the moment, apart from the fact it runs better by way of the other prob solved.

subanator · Post by **subanator** » Sun May 28, 2006 11:19 pm

Today I found that I get odd readings measured from the O2 sensor. Once it has fully warmed up, the behavior is this:
When changing gears, (the throttle closed between change) the sensor goes low, even negitive volts and when applying throttle accelerating gently it flutters and doesnt pick up until it gets a little boost. The sensor is reading crap at this stage then corrects. Back off throttle, seems ok, just when fully closed and bad reading starts.

I had checked out the throttle switch and idle switch as ok.
Checked the EGR valve as ok too.

Look at get getting another sensor now.
Roger

subanator · Post by **subanator** » Tue Jun 13, 2006 11:03 pm

Last weekend did the following:
- Repeated the fuel pressure test, but this time driving, proved ok.
- Recleaned AFM, checked signals as 1.7V idle and 3.5V blowing on hotwire with ignition on - both correct by manual. Get upto 5.0V at open throttle.
(not sure if this is correct)
- Found main loom earth on engine (on #1 intake bolt) high resistance, relating to coolant sensor and idle switch and other stuff. Cleaned and ok.

It now drives heaps better, still had similar original problem flatspot just as it starts to spool up. Next - injector clean.

subanator · Post by **subanator** » Mon Jun 19, 2006 12:04 am

Having swapped the AFM, it is not the problem. Voltage readings beween both units proved to be just about the same.
Now looking to get some hired help now

SuBaRiNo · Post by **SuBaRiNo** » Mon Jun 19, 2006 12:11 am

I will admit i have not had time to read all the posts but thought i would just add a comment. I have had very weird similar problems before... no engine codes at all... replaced the O2 sensor with another second hand one... fixed everything. Im not sure if u have investigated this yet.

They seam very fragile... i have had a new exhast made for my car... o2 sensor was fine before it was removed and refitted... but stuffed afterwards.

Dave

subanator · Post by **subanator** » Mon Jun 19, 2006 12:30 am

Dave, is yours a 4 wire O2 sensor? If it is, it will have more effect to tuning than my single wire narrow band sensor.
I was even told I could run without it without too much bother. It will only correct whilst cruising to get best fuel/air ratio.

But single wire ones are common to many vehicles, so might try another from the wreckers.

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MPFI deadspot in throttle - blog 99% SOLVED

MPFI deadspot in throttle - blog 99% SOLVED