Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

Post pictures and stories about your cars both present and past. Also post up "blogs" on your restoration projects - the more pictures the better! Note: blog-type threads often get few replies, but are often read by many members, and provide interest and motivation to other enthusiasts so don't be disappointed if you don't get many replies.
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Atodini
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#51 Post by Atodini » Thu May 10, 2018 7:10 pm

I would replace the lambda as well..... The out of range earth reading would trouble me more than a tad. Earth errors cause all manner of problems on "moderns"!!

Quick question - did you clear the fault code before testing the voltage? Most ecu's, if they detect a faulty sensor or similar, disable the input, then the fault code is generated and logged. They refuse to "talk" to it again until the fault is cleared...... So even when the fault is rectified the affected sensor won't even be monitored until the ecu is reset, so the problem will not be cleared.

John
"I thought I was wrong once - But I was wrong"...

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Zelandeth
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#52 Post by Zelandeth » Thu May 10, 2018 7:36 pm

The ECU was left disconnected from the power supply overnight so any stored codes would be wiped. Sadly no change when it was powered up. The fault is definitely here with the ECU rather than the sensor.

With the lambda sensor disconnected there should be a 500mV reference signal visible on the signal line from the ECU, that's way out of whack (at 0.7V, verified both with a digital and analogue meter). The sensor itself still seems to measure OK, though as you say it may well make sense to get a new one ordered. Sadly I can't swap it on the driveway really as I can't get any of my tools onto it because of the proximity of the steering box and chassis rail...it's an "access from underneath on the 4-post lift with fancy garage tools job" really. I played that game when changing the last one.

I still seem to have heater continuity though, and the sensor side looked OK based on what I was seeing on the meter...It's not grounded at the sensor end (unlike the lambda sensor used by the carb cars, which used the exhaust system as the ground path) anyway, so I think it may have survived as there wasn't any excessive voltage seen between the two sides of the sensor, if that makes sense - the levels were just offset with respect to vehicle ground.

At least with an ECU with a working check engine light in place it's easy enough to diagnose a duff sensor. If the input goes out of range it will trigger it (code 13: No oxygen sensor signal, 44: Lean exhaust condition or 45: Rich exhaust condition). You can actually watch the lambda behaviour in real time with the system in diagnostic mode as well, just using the light. One of the reasons I've been wanting to use this injection system from square one is that there's really good documentation out there for it - hence how I was quite quickly able to track down the wacky earth shenanigans earlier in this thread.

Toledo Man
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#53 Post by Toledo Man » Sun May 20, 2018 8:35 pm

Zel, you should check out Hub Nut on YouTube. He's none other than Ian Seabrook, editor of Classic Jaguar magazine. He's got an Invacar back on the road. I remember these back in the day. I don't suppose your Lada has an OBD port by any chance? With the right software, you could see if a laptop can talk to the ECU. Isn't it possible to have your ECU repaired?
Toledo Man

1972 Triumph Dolomite 1850 auto (NYE 751L) - The rolling restoration.
2008 Citroen Grand C4 Picasso 2.0 HDi Exclusive (MA08 WCL) - The modern.
2004 Vauxhall Vectra Club 1.8 16v (ML54 JJF) - Don't ask!

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JPB
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#54 Post by JPB » Sun May 20, 2018 11:11 pm

Toledo Man wrote:
Sun May 20, 2018 8:35 pm
Isn't it possible to have your ECU repaired?
I've done a few, the difficulty is separating the components without damage to leadouts and to the vias on the board as you try to chip away the resin. As for newer ones where many more components are surface mounted, they'll lead you down the road to clinical insanity. :evil:
Easiest are some of the early '80s units, which are often potted in pitch. A good overnight soak in petrol should provide access to everything.
John

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Zelandeth
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#55 Post by Zelandeth » Mon May 21, 2018 5:58 pm

I'm well aware of the gent behind the Hubnut videos, it was in fact his thread about reviving his Invacar which introduced me to the fact that they existed. I am *hoping* that I might be able to have mine on the road in time for it to be on show alongside his one at the Festival of the Unexceptional. Time will tell...there are quite a few things going on behind the scenes though.

The Lada's ECU does have a diagnostic port, though it uses the ALDL protocol rather than OBD or OBDII, it is actually the direct predecessor to what became the OBD protocol. Designs for how to make a serial PC interface are readily available online. This will then allow a suitable package (an older version of EFiLive for instance) to speak to it.

I do plan to attempt to repair this one, though it's going to be far easier to do once I have a known good one to compare to. The issue with mine I'm pretty sure is simply a failure of one or two transistors, though the headache is that the ones in there have custom part numbers on - so it's really hard to figure out what they are. With a known good ECU to hand, hopefully I'll be able to work it out.

Not expecting the physical side of the repair to be too hard, the traces and components are huge compared to some repairs I've done before, the only real headache is the really thick conformal coating that the board is coated with.

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Zelandeth
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#56 Post by Zelandeth » Sat Jun 02, 2018 5:48 pm

Right, we now have another ECU on hand. This was pulled from a car that was running well, and was taken off the road due to rust - so should be good.

We do have a working check engine light now...would have been nice if this had just fixed everything, but no. We do however now have a working onboard diagnostic system, which has logged two fault codes. 13 - No oxygen sensor signal and 35 - Idle speed error.

Having investigated the oxygen sensor (which was new when the conversion to injection was done), it is indeed resolutely stuffed. Both the sensing element and heater are totally open circuit. Annoying, but only £30 odd so not the end of the world. Even if having to drop the downpipe to swap it is a bit of a pain. The idle speed fault isn't one I've come across before, but I'll deal with that next.

One of the real plus sides of having used this setup is that the factory documentation is readily available and is fantastically thorough.

So hopefully making progress...

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Zelandeth
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#57 Post by Zelandeth » Fri Jun 08, 2018 8:45 pm

The fuel injected Lada Riva lives!

It also now has an MOT certificate!

The issue was eventually traced to something of a design flaw actually. The original AC Delco oxygen sensors specified by Lada for the Niva (which have been essentially unobtainable for the last ten years or so), it appears have the signal ground pin (connection C) ALSO connected through to the case. This does not appear to be the case with any of the sensors which are listed as compatible replacements.

This wouldn't be a problem aside from the fact that what should be the oxygen sensor signal ground pin at the ECU is NOT properly pulled down to signal ground...It floats at about 1.5V. So if you plug in an oxygen sensor other than the original AC Delco one - you're going to have it trigger the check engine light and report code 13, no oxygen sensor signal.

The solution is actually quite simple. Link terminal D6 (oxygen sensor signal ground) on the ECU to pin A11 (throttle position sensor & coolant temperature sensor signal ground). Once that's done, it should correctly drop into closed loop mode happily with a nice readily available Bosch oxygen sensor in place.

When it originally failed the MOT on emissions, it was showing an idle CO reading of 5.267%, with a HC reading of 188ppm. Today at the retest if blew 0.074% CO and 5ppm HC. Far healthier I think you'll agree!

I do still have an intermittent check engine light popping up due to code 35 which is an idle speed error - though the throttle position sensor reads a little out of spec at the extremes of travel, so I reckon that's the culprit. It doesn't knock the system out of closed loop or anything, just pops the light on for a few seconds now and then, so I'm not going to worry too much about that for the time being.

The swine of a thing did decide I wasn't allowed to have a quiet afternoon though, and immediately following passing its MOT decided that I really didn't need indicators did I? Was a simple problem that was quickly and easily fixed though, just the terminals in the connector going onto the flasher unit having lost their springiness. A quick retension was all that was needed.

Having now got it taxed and insured (Cheers Hagerty for offering me a price that was literally a third of what Adrian Flux wanted - even with a multicar discount!), I'm looking forward to driving it again. I'd really forgotten how much I enjoy being behind the wheel of it.

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Luxobarge
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#58 Post by Luxobarge » Sat Jun 09, 2018 7:51 am

That's a brilliant bit of diagnosis, you should be very proud of that!

So I take it that the original ECU is in fact OK? This is so often the case, it's very rare for ECUs themselves to go faulty, when I read earlier about you wanting to replace it, I confess I did think to myself "I bet that's not the problem" ;)

Well done and thanks for posting up your progress - you may not get many replies, but trust me it's good reading and much appreciated.

Cheers! :D
Some people are like Slinkies - they serve no useful purpose, but they still bring a smile to your face when you push them downstairs.

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Zelandeth
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#59 Post by Zelandeth » Sat Jun 09, 2018 9:40 am

Thanks for that. I had a lot of helpful info from Tom over at Lada Parts UK. My background is electronics and vintage technology restoration, so once I'd got a couple of key snippets of info it wasn't massively difficult to track down the fault. A 1.5V offset on an input designed to deal with a signal that only swings between 200-900mV is going to make a mess of things!

The original ECU is dead, I reckon that someone has fried several of the front end transistors - quite possibly while trying to sort this very problem.

Now I have a working one to compare to, I will have a shot at resurrecting it though (as they are evidently rather hard to find now). Was basically impossible before as all the components have custom part numbers on, but with a working unit to analyse it should be possible.

I've also just discovered that the vehicle speed sensor I need is actually still available from Lada (£8 plus p&p), so that will be another item ticked off once it arrives.

Just a bit of tidying up in the engine bay and sorting the throttle linkage needed then, and I've half a plan formed for that now.

I'm hoping at some point I'll be able to arrange a side-by-side drive of an identical car still with the carb setup to see how big the difference in behaviour really is. It's not a performance upgrade, but my observation is that it just makes the car nicer to drive as it's far less dim witted. It always felt like the fuelling system on the AFR controlled carb cars was about 1/2 a second behind what was actually going on to me on all three cars I've had with that system (Samara and two Rivas).

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Zelandeth
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Re: Zel's Fleet Blog...Lada, Saab, Citroen, Sinclair & AC Model 70

#60 Post by Zelandeth » Tue Jun 12, 2018 7:58 pm

Speed sensor has now arrived, though I need to figure out which pin is which on the connector before I can actually wire it up. It's the first one I've seen that didn't helpfully have the pins labelled.

Did have a brief moment of embarrassment yesterday afternoon when I dropped by the local hand car wash to get rid of the greasy fingerprints everywhere. I did manage to get them not to use the horrible spray cleaner though (it strips all the polish and wax off the surface of the paint). However when the were hoovering it, someone managed to snag the wire under the passenger seat (which I had forgotten was still there) that runs to the fuel pump. This then pulled it out of its (badly) crimped connector, shorted out on the seat frame and blew the fuel pump fuse. Cue the car cutting out and refusing to restart.

Only took a couple of minutes to figure out what had happened thankfully. I'll get that wiring rerouted properly soon!

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