1. Goes very nicely. However .... Prev owner reported a flat spot ca. 3000rpm. I'm getting that rarely but more (and only occasionally) a slight falter on overrun. Plug leads have been changed by dealer (which cured a v. brief spell of really rough running). Not the desired Magnecores but they are brand new. Ditto plugs.

2. Main problem - I think it is running too rich. 23-26mpg at best. Cannot tell any difference. I'm doubtful about two things, having checked some ECU voltages while running:
a. Once warm, the oxygen sensor volts move in broadly the right way but at low revs/idle the voltage swings up and down (about once per 1.5 seconds) between 0 and 0.5V (steady revs).
b. I'm having difficulty persuading myself that the injector cut out is working on deceleration (engine too loud to hear the clicks properly and can't detect a voltage drop below 1900 rpm - but suspect I'm not measuring the fuel injector volts properly. ANY IDEAS?
3. The green LED in the footwell is always on when ignition is on (don't know what it signifies).
4. The ex manifold and exhaust system has been completely changed to stainless steel with a stright thro box replacing the cat. COULD IT BE THAT LESS BACK PRESSURE IS CAUSING THE OCCASIONAL HICCUP? (2/00)

Oxygen sensor will swing at idle but it tries to stay at 0.8 V which is perfect mixture .. the swing is the ECU trying to track the mixture.

Fuel injectors .. need a current to open them I suspect and this may therefore not be voltage driven.. due to the low resistance of the coils.

No problems with low back pressure etc on exhaust .. really hard to achieve and the turbo is the main restriction in the exhaust .. typically a 2:1 figure .. so 6 psi of boost means that there is 12 psi of back pressure while a non turbo engine would have maybe 4-5 psi max at this point. (2/00)

I'm getting that rarely but more (and only occasionally) a slight falter on overrun. Main problem - I think it is running too rich. 23-26mpg at best.

Sounds like it may be fuelling. I had a problem with my custom fuel enrichment circuit, the ECU wouldn't see the signal had dropped until after I had lifted off, resulting in too much fuel for a fraction of a second - causing a falter like you describe What fuel are you using and how do you have the switch in the glove box set?

a. Once warm, the oxygen sensor volts move in broadly the right way but at low revs/idle the voltage swings up and down (about once per 1.5 seconds) between 0 and 0.5V (steady revs).

This oscillating of the O2 sensor voltage is normal idle/cruise behaviour. While the ECU is running in closed loop mode, it is constantly altering the a/f fuel mix to achieve correct stocho. mixture. (2/00)

Do you have a boost gauge?

Your turbo actuator may have worn, meaning you aren't getting much boost, and the BBR piggy back ECU is over fuelling. Mind you, it should see the boost level on it's map signal line, and so should still apply fuel accordingly - so probably ignore this.(I'm thinking aloud as it were). Boost gauge is worth getting anyway, I know someone who found he was only getting 2 psi - actuator spring had gone.

It might be worth checking the air flow meter voltages - it may be sticking, and also the throttle position switch - may not be registering closed throttle to the ECU. (2/00)

The green LED in the footwell is always on when ignition is on (don't know what it signifies).

From the BBR Turbo installation guide :
Ecu Fault Diagnosis : The auxiliary ECU is equipped with a diagnostic LED. This is illuminated at all times the engine is running. In the event of an auxiliary ECU failure the unit will 'fail safe' and the vehicle will continue running on the original ECU. In this condition the diagnostic LED will be extinguished with engine running. The auxiliary ECU must be replaced and the faulty unit returned for investigation. Authorisation is required for warranty replacement.

Recommended plugs : NGK BKR 7E11 electrode gap 1.0 - 1.1 mm

Question : You say the manifold has been changed ( very common problem, 3 out of 4 BBR installations in Belgium had their manifold cracked). On the pictures in the guide the manifold connection to the turbo goes down, so the turbo sits under the manifold, is this still the case with you're new set-up ? Judging by the pictures in the guide it would be possible to use a 323 Turbo manifold, turbo and intercooler, connections would have to be custom made though. The BBR Turbo also uses the oilcooler of the 323 Turbo (tied in with the coolant hoses), it's mounted between the engineblock and the oilfilter, might be interesting for those who have a turbo on their MX5, Eunos, Miata. (2/00)

Took everyone's advice and changed the plugs and leads (Magnecors - very good postal service by the way) but still no darts. Still very lumpy, stalling, sounds/smells like a tractor.

She's going in tomorrow as the guy on the end of the phone seemed very knowledgeable and accomadating. The worst case scenario seems to be that the BBR ECU could be gone (last price they had about 3-4 years ago was 600 pounds aaaaaaarrrrrrggggggghhhhhh!!!!!!) (2/00)

Huh, did the BBR come with a different ECU??? This is the first time I have heard that story. If you're afraid it's the ECU have a ECU of friend with a simular 1.6 MX-5 installed. That's a 10 min. job, top. If that cures the problem it's the ECU. Other suggestions.

Have cylinder compression checked.
Make sure every plug gets a spark. Could be faulty ignition coils
Is the airflow meterplug still in it's original position or has it been moved for the the BBR turbo kit? Make sure it's plugged in correctly and that no pins are bent.
If the plug has been moved and bend in an ackward position, check for wirecracks? I had this once (after a sebring installation). Car idled ok, but as soon as I hit the gas the car bogged and felt as if it was running on two/three cylinders.
If it has the BBR piggybag (Intersceptor2000), let them check the soldering on the board.

You might also opt for total removal of the Intersceptor2000 as it was no original part of the kit (AFAIK). (2/00)

The BBR did come with an auxiliary ECU, it's located next to the MAZDA ECU. The electrical couplers have to be disconnected from the original and plugged in the BBR ECU. The trailing leads from the auxiliary ECU have to go into the original control unit. The ECU could probably be replaced with an FPR for fuel requirements and MSD or J&S for the timing. Or one could use a Link ECU as Malcolm suggests.

The BBR ECU is supposed to modify the timing and fuel mixture as a function of boost and a wide variety of other engine parameters. The ECU could probably be replaced with an FPR for fuel requirements and MSD or J&S for the timing. The interceptor 2000 was introduced later AFAIK. (2/00)

I think I can help you with this. Many moons ago when BBR seemed to like MX's and offered some level of service I went there to have them sort a few things out - one of which was a rattle. The mech. showed me where this came from which was the bolt into the bracket you describe. He explained that they'd found this was also a stress point for their down-pipe( probably 'cause it's bigger and heavier than stock) and they therefore left the bolt off and let the rest of the hangers suspend the exhaust system.He remarked that he was surprised my down-pipe hadn't fractured altho' the loose bolt probably explained this - their new downpipes wouldn't have the bracket.He then removed the bracket from the bell housing so the downpipe bracket couldn't knock against it.

A couple of years later I had to have the down-pipe replaced as it had indeed fractured and the new pipe was sans bracket - no problems since then (touch wood many times!)altho' the rest of BBR's stainless steel system turned out to be cobbled together rubbish which I have since replaced.

Did you get the new manifold recently? Any problems with BBR as they may have had to make up a new batch? If you don't mind me asking - how much did they charge? Mail me off list if you prefer. I'm trying to build up a small info base on BBR turbo MX-5' as they are becoming rare beasts and will one day be worth a fortune and take over the automotive world.......... rant, dribble (5/01)

I thought I would download my BBR experiences to the list as (fingers crossed) I think I've sorted out most of the things that bothered me.

It is a bit long but might be useful to someone.

Bought the H reg car 31000 mile car 18m ago - lovely condition, well Waxoyled etc, had a fabricated stainless manifold to replace the orig BBR cast and cracked one. Fitted with a one-off stainless exhaust - a centre straight box replacing the cat. Had a Clifford alarm which also operated the doors. Nice (but heavy looking Rimstock 15x7s and 205 Avon CR somethings front and ZV1s back. Seller warned me that the lighting switch was dodgy and that for some reason the interior lights did not work.

Car went very well but on way home the lights did play up. Also switched to super unleaded and flicked over the 95/98 BBR switch, soon the car went into a really rough running spell which then righted itself.

Once home asked Tamplins to do the light switch and look at the rough running - they changed the plug leads. Seemed OK but (later) that occasional rough running problem reappeared. Set about the interior lights and decided it was alarm related. Acquired the Clifford circuit diagram from a helpful auto electrician and discovered that 5 of the (soldered) joints were incorrectly wired. I thought Cliffords only came profesionally installed!

Once I sorted out the connections it was fine - the interior lights worked and so did the various clever sensors (all silent before). The fabricated manifold started to crack and there were 2 episodes of getting it welded - the second (much more competent) job was by Mobility Welding near Hounslow station who said it would not last - too thin/thermal stress on stainless - and that the flange (mild steel) was far from flat - banana shaped would have been more descriptive - so I had that milled and we put it back together again!

At this point I noted that the bracket that secures the downpipe to the bell housing was missing so got it replaced. Subsequently the manifold did start to blow again so called BBR who (fortunately?) were having a new batch made. They said that the new ones did not crack - split flange and better alloy (Nyresist - high nickel) - and only £599 + VAT. It eventually arrived, by which time the in situ fabricated manifold had made itself into a kit of parts (some of Mobility's welds were intact but new cracks had appeared).

I noticed that the downpipe to bell housing bracket had sheared and (ref earlier emails) began to suspect that this point might be leveraging rather than relieving stress on the manifold. Got list advice (thanks to all - notably Simon Fenn and Gordon Bell) to effect that this suspicion was well founded. BBR and Tamplins were a bit vague but also thought the bracket unnecessary. At this point you can understand that I was paranoid about breaking my new manifold so I looked the exhaust over and found that the bracket immediately behind the cat was also absent. Now to lose one fixing is unfortunate but two seems careless. On a NA car this situation is common with funny exhausts but with the added weight of the turbo I decided that I wanted the heavy back end of the system supported to reduce loading on the front end.

This involved a mini saga in constructing a flange and sleeve to go on the back exhaust section so that it would mate with the back of a new JR cat from Moss (lighter than the old one so less load/paranoia at the front).BTW why ARE the flanges at funny angles?? The job also involved going to Central in Kilburn for scrap exhaust to get the missing bracket.

So now the car has a 'standard' BBR set up once again in that all the pieces properly interchange with factory or BBR bits.

Next on the list was those wheels - I'd already ditched the tired front Avon CR thingy fronts which were alarming in the rain - G'year F1s 195s instead. The back 205 ZV1s seem fine - I don't drive that hard but they are 'reassuring'. First I went back to the previous owner who had told me he had earlier wheels which he'd replaced because they looked rough. In fact these were not much lighter, and Gordon inherited them. I went for the 'offer' on mk2 5 spokes from Tamplins (who I've found to be really helpful). The car definitely felt better - mainly because bumpy roads felt less bumpy at 7lbs less unsprung weight per wheel.

Oh yes - the occasional rough running - that got worse. I had already done the Magnecore thing but it came and went anyway. I tried various things - I had fiddled with the air bleed screw on the air flow meter (yours should be sealed, mine was not) and with John Cookson's advice ("don't") and his neat AF meter I got the idle mix correct when the engine was running without the O2 sensor - this improved pick up but didn't fix the gremlin. I changed the O2 sensor which seemed slow to react - and went the 4 wire route - which should at least help the cat help local air quality. Checked the thermosensor, spark plugs, cleaned the AFM plug and drained the petrol too (after 10 years a very small amount of crap and water in the last 150mls in the bulge at bottom of the tank). Then the rough running persisted for longer and I was able to swap bits with another 5. Coil pack, leads and ECU all got changed. Took the BBR piggyback ECU out too. This produced a positive result in that NONE of these swaps made any difference, it was rough throughout. It is not often you get that luxury with an intermittent fault!! However, the following morning all was well again. Turbo? Had it checked out by Boxer in Ashford (TurboTechnics agents) and it seems fine.

So I've concluded that I either have a poor contact at the ECU plugs or a dodgy earth or two - and so have started cleaning up the obvious earth points - the neg battery terminal was poor for a start. The frequency of the problem has decreased and seems related to changeable weather - fine when really wet or dry but I think it might be influenced by cold mornings after warm nights. Am eventually going to Switchklene the ECU plugs and do the recommended ECU earthing thing (see dlralt) and then the rest of the earths - followed by that alarm/immobiliser circuit. Meantime it is so occasional I can live with it.

What else - I put in a rollover bar, the Safety Devices 'Speedster Bar' - double hoop, well braced, I used the Mk2 version so that I could in future upgrade the hood/window and also it lets the plastic window lie pretty flat. Also I have spent some needle and thread time on the hood zip - quite therapeutic after greasy spanners and voltmeters. On zips my recommendation is candle wax - once a month.

Believe it or not, I bought this car so that I would not have to spend time working on it but old habits die hard (the other car is a 69 Elan). I've now got the car how I want it and hope that it will continue to be as nice to drive as it is now. (7/01)