notfub

iTrader: (4)

I’m in need of some advice. My car is a 2001 Bugeye with the following spec (Walbro 255 lph fuel pump, TD05 16g turbo, STI TMIC, Blitz induction kit with replacement K&N Cone, STI 440 lpm pink injectors, TSL ported equal length exhaust manifold and full decat system, Ecutek remap & forged engine by Paul Blamire at Zen Performance). It’s running 7b spark plugs that are less than 3000miles old, these have been out to check the gaps and refitted.
While the car performs well I have had a series of annoying problems that may relate to a MAF, coilpacks, valve clearance or Lambda etc and I want to solve them and enjoy the car without worrying something more serious may fail.

I thought I’d put all the issues I have with the car, some which may be irrelevant but by putting all of this here it may allow you to make a good judgement call.

Problem 1 – Downhill hesitation
While on a motorway journey (engine warm), when travelling downhill and lifting the throttle a little, but not completely off the pedal, the car misfires or hesitates. You can feel the slight judder as the car does this. Just nudge the throttle down a little more and the misfire vanishes. Lift off slightly again and it’s back, even my 15 year old son noticed it yesterday. There are no cells reported or flash cells on the dash, just the slight misfire. To emphasise, the throttle is still being pressed but just enough to maintain the cruising speed, then it misfires/hesitates. The misfires and not big jolts as it were, just gentle stutters.
Any ideas what could be causing this problem?

Problem 2 – Stalling
When pulling up to a junction and dipping the clutch to brake for the junction the car will cut out. It’s has happened about twice in the last six weeks or so and seems completely random. Car is fine before and after the stall. This happens very infrequently but I wanted to mention it as it adds to the diagnosis of an overall problem perhaps?

Problem 3 – Jumping/Kangarooing
This is more noticeable when setting off in 1st gear or after just changing to 2nd gear. If I’m not very gentle and progressive on the throttle, the car will jump or kangaroo for a few seconds before the revs settle and the car pulls cleanly. Now don’t confuse this with drag starts, this is normal driving when pulling away from a junction. This happens when hot or cold and could be an Impreza trait bit my old classic never did this. Any ideas?

Problem 4 – Flashing Cell & P0301 Cyl 1 misfire detected.
On the motorway yesterday the car was flashing the cell light when cruising at 70mph under very very slight load on the flat. I could stop the cell by lifting off the throttle be a small amount, almost negligible really. I got to my destination without a permanent cell and the car felt fine generally as in if I’d not seen the cell flash I’d have been none the wiser.
On the return trip the cell came on permanently and the scangauge showed one fault stored as the P0301 cylinder 1 misfire detected.
This one could be the “neutral position switch” BUT my gearbox has been changed to a later TY754VN6AA spec so it’s a newer switch and one which may be more robust than the original fit Bugeye spec?

Thanks for your help.

STiFreak

iTrader: (4)

Ok, here is what I would do:

It sounds like your misfire is worst when in closed loop (cruise and light load) and therefore running leaner.

Swap the coilpack from Cyl 1 to Cyl 3 and see if the misfire moves with it. While it is out, pull the rubber boot off and check to see if there are any visible issues which may be causing a poor connection.

If you know someone woth a wideband, ask them to check what AFR you are running at cruise (should be around 14.4 to 14.7). You may have an issue with a failing front O2 sensor.

If this doesn't solve the problem, then it may be injector related (slight blockage reducing fuel to one of the cylinders). Ideally you want to get the injectors removed, ultrasonicallly cleaned and flow tested ... but this in it's self is not cheap (about £15 an injector).

Check out this site for more ideas.
Engine Misfire Diagnosis

notfub

iTrader: (4)

Thanks for taking the time to reply STiFreak. I'll pop the coilpacks out and give them a good once over as well as checking the plugs for a 3rd time. I may even just buy another set of plugs to be on the safe side.

I've asked in the Wales section about checking AFR's locally and I've had an offer of the use of a VI Monitor (can do AFR's apparently).

If the injectors were playing up, would they not cause problems in all driving/throttle conditions?

It's also been suggested to me that the MAF can cause some symptoms BUT I'd have thought that MAF issues would be more noticable on boost or in open loop conditions.

STiFreak

iTrader: (4)

Best thing to use on the coilpacks would be electrical contact cleaner.

Does the VI Monitor have a proper Wideband O2 sensor or just read the factory narrowband sensor? Proper wideband would be better if possible.

Could be MAF, but less likely IMO ... easy to check if you can find someone else with a newage MAF to swop out and test.

Injectors with a slight blockage would be more likely to show at low injector duty (closed loop and light load).

notfub

iTrader: (4)

Thanks for the continued advice STiFreak

The VI Monitor (now I've got my paws on it) plugs into the OBDC plug so it's going to use the narrowband lambdas. It has data logging so I can analyse the output after taking the car for a good run. I know by using the narrowband sensors I'm not going to get a super accurate reading but it may just be enough to identify an issue.

Hope it's not the injectors but only time will tell and i'll update this thread with any findings along the way.

Jolly Green Monster

iTrader: (4)

so the car was fine... nothing has changed?

Simon

notfub

iTrader: (4)

No the car is still playing up. I've not had a chance to check/swap the coil packs/plugs yet Simon (original post was yesterday ). I was out last night in the car and got a flashing cell again, but not solid cell so couldn't read the code on my Scangauge II.

The car was still dispalying the "downhill hesitation" symptoms on the flat at 30mph in 3rd going through a built up area too .

The stalling is very infrequent but thought i'd mention it as it may be linked to the root cause or causes.

Also the car seems to be using more fuel than usual.

Other than the flashing cell and the hesitation, the car behaved itself last night.

I'm going to inspect and change the coil packs over today and rig up the VI Monitor to log a couple of runs (after I've read the manual and upgraded the software).

Jolly Green Monster

iTrader: (4)

sorry I wasn't very clear..

the car WAS fine... and all of a sudden these problems started happening? nothing to do with swapping stuff around but before these problems occurred the car WAS fine?

Nothing has changed since it was fine and now isn't? you haven't changed fuel station, fitted a dump to atmosphere dump valve etc..

Simon

notfub

iTrader: (4)

Sorry Simon.

Problems 2,3 & 4, Stalling, Jumping/Kangarooing & Flashing Cell & P0301 Cyl 1 misfire detected have been there since I bought the car. Problem 1, downhill hesitation has only appeared since the car has been back on the road.

The cell flashing has been more prominent since I did some work on the car last week. This was changing the fuel lines under the inlet manifold to cure the cold weather bugeye fuel leak issue. A 2nd hand metal fuel line from a 2003 STi was used with new 7.6mm diameter fuel hose. Fuel lines were double clamped where possible for piece of mind. New gaskets were used when putting the inlet manifold back onto the car. The boost solenoid was also cleaned out (green plugs under dash connected and brake/carb cleaner added to both pipes). I added a larger TMIC (STi instead of WRX) and replaced the Blitz SUS induction cone with a similar sized K&N. I also removed a Forge VTA BOV and replaced it with a stock OE recirc valve.

I had the larger STi TMIC with the car as the previous owner was running it and put the WRX one back on to sell. The car had made 6bhp extra at Zen with the larger TMIC.

I have a feeling your going to tell me I need a map tweak?

Jolly Green Monster

iTrader: (4)

it does sound like it needs checking if nothing else.

Simon

L.J.F

iTrader: (31)

i would say so as you have made a change to the induction, i very much doubt they are like for like!

notfub

iTrader: (4)

I'll pop the blitz back on at the same time I check the plugs/coil packs (later today). I'll report back on the results.

Thanks for the feedback so far

Jolly Green Monster

iTrader: (4)

Hence why I wondered what you had changed.

notfub

iTrader: (4)

For Info : Here's a pic showing the difference between the Blitz SUS and K&N Filter cones.

Jolly Green Monster

iTrader: (4)

more to do with the efficency of the filter than how it looks

notfub

iTrader: (4)

Update
After failing to log AFR's with the VI Monitor I did a little research and ended up doing some datalogging with Romraider and an old ODB2 cable I had from my Seat Leon days

I've left the car as is and not swapped the air filter (so K&N is still on) and I've not checked the coil packs.

I read the Closed Loop article on the Romraider website and managed to log the following parameters;


-Time
-A/F Correction #1 (%)
-A/F Learning #1 (%)
-A/F Sensor #1 (AFR)
-Engine Speed (rpm)
-Injector Duty Cycle (%)
-Mass Airflow (g/s)
-Mass Airflow Sensor Voltage (V)
-Vehicle Speed (mph)
-A/F Learning #1 A (Stored)* (%)
-A/F Learning #1 B (Stored)* (%)
-A/F Learning #1 C (Stored)* (%)
-CL/OL Fueling* (status)

Obviously there's a lot of data there and trying to keep the car in closed loop and to hesitate/miss was a little tricky. Now I know I managed to get the car to misbehave on the test run but can someone give me a few pointers on what to look for? The narrowband AFR's do seem a little erratic, especially when coming back onto closed loop from a time at open loop but perhaps that's to be expected?

I guess I need to have someone alongside me operating the laptop on a specific piece of road I know I can get the car to hesitate going downhill.

I'm happy to email my CSV log file to anyone who's more in touch with this sort of thing

notfub

iTrader: (4)

Scatter Plot

Here is a scatter plot of the entire closed loop activity from a recent 15/20 minute datalog. This is mixed driving at mainly low speeds (highest 60mph).

Some of the peaks have occured around the time when the car has just switched back to closed loop from open loop.



MAX AFR = 25.37
MIN AFR = 11.37

Any thoughts anyone?

Jolly Green Monster

iTrader: (4)

Can you plot throttle position on the same log?

most of the leaner high afr number is probably when off the throttle.

Simon

notfub

iTrader: (4)

I can only see the following related throttle logging options in ROMRaider while not connected to the car;
- Throttle Motor Duty (%)
- Throttle Opening Angle (%)

I believe more options are available in ROMRaider when it's communicating with the ECU. I'll make a point of logging the "throttle" related items in another log later today and put up another graph.

Thanks Simon.

Also want to thanks STiFreak for his PM's and help

STiFreak

iTrader: (4)

Throttle position = Throttle Opening Angle (%)
Throttle motor duty is not needed.

Log Engine Load.

You want to try keep your logged parameters to a minimum ... the more parameters you log, the less often each one is logged.
You can probably drop the following from your logged parameters to improve the resolution a bit:
-A/F Learning #1 A (Stored)* (%)
-A/F Learning #1 B (Stored)* (%)
-A/F Learning #1 C (Stored)* (%)
-Vehicle Speed (mph)
The logs you sent me showed it adding 3% learned correction in A, but that was constant through the log and is not excessive.
Easier to use the Learning View tool after a drive to check these values.

notfub

iTrader: (4)

Did some logging today with the following parameters;

- A/F Correction #1 (%)
- A/F Learning #1 (%)
- A/F Sensor #1 (AFR)
- CL/OL Fueling* (status)
- Engine Speed (rpm)
- Mass Airflow (g/s)
- Mass Airflow Sensor Voltage (V)
- Engine Load* (g/rev)
- Throttle Opening Angle (%)

I've managed to put together a chart in Excel which shows the Closed Loop data only (open loop CL/OL Fueling status = 10 has been removed).

Here's a plot of CL AFR's (in red) against Throttle Opening Angle.

notfub

iTrader: (4)

I've bitten the bullet and decided to book my car in with Paul at Zen.

In the meantime, I've put the Blitz filter back on instead of the K&N to see if things settle back to how they were before. I'll also check the plugs, gaps and coil packs tomorrow so I'll know everything is ship shape before the trip up to Wellingborough

notfub

iTrader: (4)

Bit if a delay in responding due to starting a new job & staying away from home in the week.

Right, went to see Paul at Zen armed with a different 2nd hand MAF plus an additional spare and my original, just in case. The K&N was back on and we were ready to tweak the map. Paul took a quick set of readings from the car to check what the MAF was doing. He then swapped in a known good MAF and confirmed that the 2nh hand one I'd got was fine

The weather was closing in at this stage with a coupe of inches of freah snow on the roads....not good for mapping. Paul took my car out for three/four logging runs, coming back to the workshop to analyse the results on the laptop and tweak the map.

Basically the issues I was experiencing were down to a dirty MAF plus the addition of a more efficient K&N air filter. The MAP tweak has worked and the car doesn't miss or produce any flashing or solid CELL's now.....Result!