1991 450SE Flapper or Hotwire?

1991 450SE Flapper or Hotwire?

Author
Discussion

hillclimbmanic

Original Poster:

668 posts

153 months

Thursday 24th October 2024
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A bit of a stupid question, but my car isn't with me at the moment, so I can't look for signs - Stepper, etc..

When did the Hotwire system come into play?


Manic

BritishTvr450

467 posts

8 months

Thursday 24th October 2024
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Until someone else more informed comes along I’ll add what I think I know.
I once owned a 1980 XJ6 Jaguar which used the Bosch efi system that had what I think became the CUX system used on Rover based vehicles. It worked very well.
So an early version of the afm meter and Ecu very similar to what later became the 14 CUX which appeared on the Griff and Chim cars and possibly the last of the wedge cars.
I seem to think earlier Wedge cars used the earlier CUX system that does indeed look very similar to the later 14-CUX system but is slightly different.
That doesn’t answer your question but does offer some background information as to the system in general.

Yatesy350i

1,001 posts

145 months

Thursday 24th October 2024
quotequote all
hillclimbmanic said:
A bit of a stupid question, but my car isn't with me at the moment, so I can't look for signs - Stepper, etc..

When did the Hotwire system come into play?


Manic
Hi Paul

When you get the car back. Have a look at the ECU wiring behind the drop down panel in passenger footwell. If there is a white plug it's a Hotwire and you can plug into it with free Rovergauge software. You just need the cable. One on eBay at the min.

Can be seen in the centre of the pic below. Very useful and quire easy to use. You can manually test the Stepper and also record sessions while driving. Pinpointed my CTS issue.


[url]|https://forums-
images.pistonheads.com/378693/202410244159349[/url]


pwd95

8,407 posts

247 months

Thursday 24th October 2024
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They started using the hotwire system during 1990 so yours is likely to be hotwire. Do you have a pic of the engine?

Wedg1e

26,898 posts

274 months

Friday 25th October 2024
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I'm fairly certain it would have had to be the hotwire setup as the 4CU flapper would have run out of puff before a 450 got into 4th biggrin
The ECUs and AFMs are visually a lot different, the flapper having a curved black cover while the hotwire's is more square.

KKson

3,441 posts

134 months

Saturday 26th October 2024
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Wedg1e said:
I'm fairly certain it would have had to be the hotwire setup as the 4CU flapper would have run out of puff before a 450 got into 4th biggrin
The ECUs and AFMs are visually a lot different, the flapper having a curved black cover while the hotwire's is more square.
My 1989 450 SEAC runs flapper, but with the larger Jaguar AFM.

Wedg1e

26,898 posts

274 months

Saturday 26th October 2024
quotequote all
KKson said:
My 1989 450 SEAC runs flapper, but with the larger Jaguar AFM.
Interesting. I thought that setup topped out around the 4.2L mark, guess it must just be like a tap between the tank and the cylinders biggrin
I'm guessing it has the throttle body bored out and uprated injectors, bigger trumpets etc.?

I did have a Jag AFM on the 390 for a while but took it off as I thought it was causing a running problem. That turned out to be a dying pickup in the distributor and I've never got around to refitting it, partly because I got such a good dyno graph at the BBWF one year (2010?) that I decided to leave it alone. With it on, fatter injectors and the fuel rail at standard pressure, it was like being thrown off a cliff, but the fuel consumption was horrific. I stick with fatter injectors and the rail pressure turned down, but have toyed with a solenoid bypass system linked to a switch so you can have Ludicrous Speed when required...


Edited by Wedg1e on Saturday 26th October 20:46

KKson

3,441 posts

134 months

Saturday 26th October 2024
quotequote all
Wedg1e said:
Interesting. I thought that setup topped out around the 4.2L mark, guess it must just be like a tap between the tank and the cylinders biggrin
I'm guessing it has the throttle body bored out and uprated injectors, bigger trumpets etc.?

I did have a Jag AFM on the 390 for a while but took it off as I thought it was causing a running problem. That turned out to be a dying pickup in the distributor and I've never got around to refitting it, partly because I got such a good dyno graph at the BBWF one year (2010?) that I decided to leave it alone. With it on, fatter injectors and the fuel rail at standard pressure, it was like being thrown off a cliff, but the fuel consumption was horrific. I stick with fatter injectors and the rail pressure turned down, but have toyed with a solenoid bypass system linked to a switch so you can have Ludicrous Speed when required...


Edited by Wedg1e on Saturday 26th October 20:46
Yes, bored out plenum, not checked the trumpet size TBH, big old Bosch injectors and solid lifters. Goes quite well.

pwd95

8,407 posts

247 months

Saturday 26th October 2024
quotequote all
My old 450 SE was on the flapper system. Bored out plenum etc. Made 283 on the rollers at BBWF 2010ish.

hillclimbmanic

Original Poster:

668 posts

153 months

Thursday 31st October 2024
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Thanks Guys! I have found an old (Dirty!) engine bay photo, and I can see that it has a stepper motor?




Wedg1e

26,898 posts

274 months

Thursday 31st October 2024
quotequote all
It does.

And a Foxguard alarm biggrin I was fitting and repairing those in the early 90s... not quite sure what I've done for the last 30 years though confused

adam quantrill

11,584 posts

251 months

Thursday 31st October 2024
quotequote all
Looks a bit like mine. Mine has a fault where it draws about 1A all the time, so it's switched off with the key. Don't spose you have any schematics?
Otherwise I'll troubleshoot it blind.

Wedg1e

26,898 posts

274 months

Friday 1st November 2024
quotequote all
adam quantrill said:
Looks a bit like mine. Mine has a fault where it draws about 1A all the time, so it's switched off with the key. Don't spose you have any schematics?
Otherwise I'll troubleshoot it blind.
I have the feeling you've asked me this before, did I not send you the wiring loom colours some time ago? That's all I had, never had more than odd scribbles regarding transistor types for the siren output stage, programming for the encode/ decode chips etc.

The Foxguard brand was just one of several applied to the same range of alarms (Stinger was another); each range had variations in what capabilities the units had e.g. central locking, immobilising, window closure over and above the basic shock/voltage drop/ultrasonics detection. All the PCBs were the same, they'd just omitted a few components.
We worked out that it was cost-effective to buy the base model of the cheapest brand from the wholesalers, take them apart and add the missing components (usually just two or three relays, couple of transistors and a few feet of wire) and sell them out as the top range model from the higher-end brand than it was to buy the full-spec version to start with biglaugh
Sometimes feel like I've been on minimum wage ever since irked

I'd be wondering whether you have one or more leaky electrolytics (especially tantalums) pulling the supply down and causing the parasitic drain - it is 1980s tech after all. I'd also check the siren driver stage, from memory it was transformer-coupled and you might find the transformer getting warm if there's some leakage current through the transistors (TIP32C rings a bell, but it was a long time ago!).

pwd95

8,407 posts

247 months

Saturday 2nd November 2024
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Yes, hotwire. thumbup

Wedg1e

26,898 posts

274 months

Saturday 2nd November 2024
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pwd95 said:
Yes, hotwire. thumbup
That's definitely the hotwire airflow meter.

hillclimbmanic

Original Poster:

668 posts

153 months

Monday 4th November 2024
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Thanks Guys! I was pretty sure, but doesn't hurt to ask!


Manic

adam quantrill

11,584 posts

251 months

Friday 8th November 2024
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Wedg1e said:
I have the feeling you've asked me this before, ....
I'd be wondering whether you have one or more leaky electrolytics (especially tantalums) pulling the supply down and causing the parasitic drain - it is 1980s tech after all. I'd also check the siren driver stage, from memory it was transformer-coupled and you might find the transformer getting warm if there's some leakage current through the transistors (TIP32C rings a bell, but it was a long time ago!).
cheers I'll check those big caps inside!

Wedg1e

26,898 posts

274 months

Wednesday 27th November 2024
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adam quantrill said:
cheers I'll check those big caps inside!
I just found the emails where you previously asked me about the alarm... it was January.








2019 biggrin

hillclimbmanic

Original Poster:

668 posts

153 months

Tuesday 3rd December 2024
quotequote all
Wedg1e said:
That's definitely the hotwire airflow meter.
Could the Foxguard alarm be causing my starting problem? After it hits operating temp, it will not start, spins over really well but will not catch...

SLB

261 posts

250 months

Wednesday 4th December 2024
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hillclimbmanic said:
After it hits operating temp, it will not start, spins over really well but will not catch...
I would suggest that's the ignition amplifier on the side of the distributor starting to fail. In 34 years of driving TVRs the only time I have ever not made it home under my own steam was when my amp did this at lights 1/2 mile from home. I got the wife to tow me back and she split the front spoiler doing it. If I had waited 20 mins to cool down it would have started and got home safely. The amp is now placed by the coil using the Lucas re-routing kit and no issues since.