NJ's Basingstoke Build (UK)

[jgilbert]

N.J. Loving the rear end tube work. Best I've seen to date.

Some very nice styling and attention to detail going on. Keep up the good work and new ideas.

[NJ.]

Thanks gilbert. Trying to mix things up a little rather than copying everyone else ideas.

So, been working on the loom as I want to get the mounting points and routing figured out before sending the frame for powder coating.
I've got the loom all roughly in place and figured I'd get the car started again.



I was hoping proper grounds would fix the issue but the car still isn't behaving and I'm hoping someone can help.

Symptoms are - when cold idle is way high @ roughly 2000 rpm.

Once it warms up it must trigger something as the idle then drops down but starts hunting between 900 ish and 1500 rpm?
If you click the image below it should take you to a video of this hunting.
It only hunts between 900 and 1500 the higher revs are me blipping the throttle.




Anyone seen this before or have any ideas for what to check?

It wasn't doing this before I stripped it so I'm guessing I've not put it back together correctly or I've knocked/broken a sensor somewhere...

[gwnwar]

Got gas in tank?.. vac. leak.. (hose or intake tube)

[NJ.]

Thanks Gwnwar， I know gauge says it's low but it's had probably 7-10 litres in there. Guess I can top it up if you think that could be an issue.

Possibly a silly question but will having no brake fluid in the Mc affect the vacuum boost line in anyway?

I stripped apart the whole intake side and reused the gaskets so I guess I need to go through everything and check for leaks.

[cooltech]

I would look to idle air control (IAC) valve as cause of the RPM hunt. At idle, the throttle plate is very nearly completely closed and the ECU allows air into the engine through the IAC to control target idle RPM. So, something may be physically wrong with the IAC or perhaps the wiring isn't quite right. Definitely something amiss in this area. Too high of expected RPMs is generally a vacuum leak but vacuum leaks tend to be pretty consistent (the same high rpm). The fact that you are surging but get down to 900rpm on the low side leads me to believe a vacuum leak is NOT an additional problem for you. FYI: One of the better ways to chase down a vacuum leak is to use a can of starting fluid and start squirting (modestly) suspect areas of the leak. You will notice a change of RPM when you find the source of the leak. On some Miatas, you could experience a leak around the fuel injectors as those seals become dry/hard. In summary, I advise you to look first at IAC operation.

[iparnell]

May be a strange question but do you vape? The reason I ask is coz I used a smoke test to pinpoint my vacuum leak. Pull off any vacuum pipe, take a huge intake of vape and blew it in...worked a treat. 👍I'm not encouraging smoking in any shape or form but it worked for me..😉

[sheffjohn]

Feb 4, 2017 0:38:41 GMT iparnell said:

May be a strange question but do you vape? The reason I ask is coz I used a smoke test to pinpoint my vacuum leak. Pull off any vacuum pipe, take a huge intake of vape and blew it in...worked a treat. 👍I'm not encouraging smoking in any shape or form but it worked for me..😉

That's genius. Should find any massive leaks easily !

[NJ.]

Thanks for all your suggestions guys. I will have a look at the iscv tomorrow. It is humming quite loudly which I don't remember it doing before I took the car apart although reading online that could be normal.
I don't vape but also heard of this method (with cigar smoke though...)
Will spray starter fluid around the various pipes and see what happens.

[phocup]

I would check ignition timing and confirm its correct.  Easy enough to cross that one of the list before hunting for leaks.

    

[NJ.]

Feb 6, 2017 6:49:45 GMT phocup said:

I would check ignition timing and confirm its correct.  Easy enough to cross that one of the list before hunting for leaks.

    

Mines a mk2 NB which I believe has electronic timing?  
So my thought is if the timings ECU controlled then its either in time or not (unlike the mk1 with the rotatable CAS?)
Not being difficult, just want to confirm thats worth checking as I'll need to buy a timing light if so... 

So, some developments. Checked the TPS - as per this guide.

forum.miata.net/vb/showthread.php?t=388269

All in spec for the resistance measurements.

Ran the engine again until it got hot and hunted.
Turned off car.
Disconnected the IACS and started.
Idle then remained steady at 8-1000 ish rpm.(can't remember figure but was much slower idle and steady).

So, I guess that means two options.
A) the IACS is sticky/broken - I have taken it apart and cleaned with brake cleaner but maybe its broken?
B) another sensor is off and the ECU is trying to use the IACS to compensate?

For now I have ordered a replacement throttle body complete with IACS and TPS from a used (working) 1.8.
I'm not 100% convinced that either sensor is broken on mine, but I did manage to trash my idle adjust screw in the TB fiddling around so will need a replacement anyways.

So, I'm hoping once the new TB + ISCV arrives the problem will be fixed, but if not the next items to investigate seem to be

O2
Coolant temp sensor
MAF

[snowbird1]

Not sure if your engine has a coolant connection to the ISC - if it has check the coolant flow from the rear of the cylinder head to the t-stat housing, I had a car where this was blocked at the rear of the head and it screwed up the idle.

[NJ.]

Ha, no update since Feb, how time flys....

So, last update I was stressing about the idle control - well a second hand throttle body, complete with IAC and TPS sensor fixed that problem.

I added some harness guides to the harness bar as others have done.



I added some side panels to protect the passengers from wind and rain, but have a plan to make them from PETG so they are clear.  Card templates cut on a laser were used to tweet the fit correct and get the bolt mountings welded in place.



I wasn't happy with the headlight brackets I previously made - and deciding to use DRL's meant I need to redesign the mounts.
They turned out much better than the first attempt and will fit the wiring for the headlights and led's inside.  For the IVA, the DRL cap will be replaced with a solid front plate and fit after the test.




Found a new steering wheel to replace the stock which had an airbag, nothing special but I think it should pass the radius test...



I added some protective bars for the ABS and brake booster that should keep the IVA mans balls at bay...



And now the exciting stuff....
Got the frame back from powder coating.  Went for 'polar white' and it looks great in the flesh.  Need sunglasses in direct sunlight.....  



First job after getting it back was a wash and a coating of Carpro's CQuartz and Reload. Hopefully that'll help keep in whiter for longer as it's a nano coating that's super hydrophobic. 

I got the ali floor and some other bits powdered black along with the frame. So the next job was to fit the floor. I added some carbon effect vinyl which looks pretty good in fairness and contrasts well with the white frame.







Fuel and brake lines went in next.  Heat shrink tube was used to give some protection and an OEM look.



Rear handbrake and brake/fuel lines were fit before dropping the frame onto the PPF.



Changed the oil in the gearbox and diff, details below in case it helps; 
Gearbox - Redline RED LINE Synthetic Manual Transmission 90 MT90 75W-90 GL4
Diff - RED LINE Synthetic Gear Oil 75W-90 GL5

On Saturday, we dropped the frame onto the PPF and got the springs back on. (Thanks again for the help Dad/Dave...)



I'm super pleased with the above pic and with how the car is looking and coming together.
And that pretty much brings us up to speed.

The race is on to get it IVA'd. Just a quick question on the IVA process, after the test is passed, how long does it take to get the forms back from the DVLA?

Trying to put some semblance of a project plan together....  

[d7lcd]

Your build looks great.
I'm also in Basingstoke with an Exocet drop me a PM if you want to meet.

Luke

[jgilbert]

Why is it the smallest garages produce the BEST builds?

Like the attention to detail, looking very good.

Took about 4 weeks to get my Plate after IVA. However I thing the process has improved since my IVA.

[dave]

Hi Nick,
Car is looking pretty good so far, have you decided how you are mounting the fuel filler as I am mounting my tank the same way.
Cheers Dave