hairball29

The plot thickens, folks. I have an SCT X4 for tuning. As you probably know, they plug in to the OBD port and nowhere else. They don't have separate power. I use the X4 in conjunction with the AF gauge to report the AF ratio for logging. Turbo Tom is tuning the car for me. Anyway. I had suspected my no-start was also happening with the X4 attached, and i just confirmed it by reading the voltage on the output side of the Fuel Pump Driver Module. When trouble comes, the voltage reads 0V on firing and the engine does not run. It reads 8V (ish) normally at idle. I don't think this is the only ECU symptom as it's not consistent, but it's the only easy way i have to measure if that ECU is acting up and a 0V definitely. My findings are: - X4 connected to OBD and AF disconnected and O2 disconnected from AF - no start - gauge attached but no O2 - start - gauge attached with O2 - no start - gauge and O2 connected but with wires completely pulled away from the dash and the PATS sensor - no start Apart from current draw, the only differences I am aware of are that the gauge alone uses an earth to the chassis. If the O2 is earthing through the exhaust, then it might be going through the motor and back to the battery. Today I have been under the car to clean up and ensure a good connection for the engine to frame earth. The battery to engine earth is new. I also made a new earth strap and connected to the body, but nope. Symptoms remain as above. I even ran a jump lead from the battery negative to the exhaust to give the O2 a different earth. Same I can get around all the above my unplugging/turning off everything before starting, but it's really doing my head in and i'd love to know why it's happening. Perhaps something's messing with the ECU's earth, but why don't the headlights or radiator fan cause trouble.

I haven't contacted them, but that is a good idea. Mainly I didn't because this used to happen with my USB in the cigarette lighter, too. This was before i had the gauge so i thought it was something more broad. I'm going to play with it some more and see if it is EMI from the wiring and device. I'll update you soon!

The O2 is the device that came with the gauge. It is a 6 core cable between the gauge and the O2 and that carries, live, earth so i cannot easily separate the gauge earth from the O2 earth. The 6 cores come together in a small plug which attaches to the gauge. I had suspected the PATs and moved the gauge, but that was before I noticed the unplugged O2 improves things. The excess O2-to-gauge cabling is under the dash so if that's what's making EMI, then it might be a factor. I'll go move it later and get it as far from the PATS halo as i can to see if that changes anything and report back. The gauge and ECU are about half the cockpit apart. The gauge is behind the gear stick, and the ECU is at the bottom of the passenger footwell Disconnecting the gauge will allow me to start. Currently i just pull the connectors apart, then reconnect, but i need a switch would be a more good version of that crudeness. I did try attaching the gauge to switched live, but of course switched live is on before the engine starts so it had no positive effect other than meaning the gauge goes off when i turn the ignition off. thanks for your input, everyone

Yes, the gauge reads fine. It shows various AF readings as i change throttle positions. The car never dies once it's running, whether with the gauge, the o2 or both are plugged in, but they have to be connected after the engine is running or we get a no-start.

Hi, Once the car's running, I can then plug in the AF or O2 or both and all is well. It doesn't upset the running at all, it only makes trouble on startup.

Just tried the car-to-car jump and confirmed the connection was bringing in the same voltage as the running donor car. No change. Still won't start and with the same symptoms. Soon as i unplug the AF, problem goes away.

Hi, there’s no more inputs or outputs on the ecu when the af is on as it doesn’t connect to the ecu, it’s just the gauge and the sensor powered from the battery

Hi, guys Typically i start the car by unplugging the AF (connected to the O2), start it, then plug it back to run my AF. I have never had a problem when doing that. it runs great during the plug in, there's no discernible changes to the motor, revs or anything. When i was really struggling with this, i would connect the battery to a jump/charger device which fed it 13.x volts, and a few times the problem would go away. i have not connected it to a running car, so I'll give it a try. I had wondered about jump starting it down a slope with gauge connected, meaning there'd be no starter motor pulling juice, or is that a bad idea? I have to figure out how to measure the voltage into the ECU. i have the pin-out from the focus manual, but i don't have a thin enough probe to get in there whilst it's connected. I have probed it whilst disconnected and it's at 12v fwiw. Could the starter be bad and drawing too much voltage? I have heard that opinion from another Seven person. thanks

Hi, all thanks for the input. The 02 sensor has a 6 core cable that plugs in one end at the gauge, and terminates at the O2 sensor JohnCh, i just went out to test again. When i first started working on this, i just had a cigarette lighter socket with a dual USB plug in it which seemed to break it. Just now i tested and that seems to not be the case now. At least today! this is what i found: - Cigarette lighter with USB plug connected to my phone and charging (so drawing current from the battery) and wired in using the same connections as the AF above - start - AF gauge plugged in as above NOT connected to O2 - Start - AF gauge plugged in as above and connected to O2 - NO start So, it seems that the car will withstand a small amount of juice being drawn through the battery and back into the chassis, such as the USB charger, but perhaps when the O2 sensor heater draw is added, the no-start comes back. now, i should say that it failed to start pretty consistently before with just the USB plugged in, but i couldn't consistently recreate that just now. there were a couple of non-starts Do you think it's possible that the extra draw from the AF is lowering the voltage too much for the ECU to stand? I thought stock ECUs could stand a drop to below 10v? does anyone know what their battery drops to when cranking?

Hi, It's an AEM 30-4110 UEGO gauge. You're right about the exhaust, but all i can tell you is that the resistance between the pipe and the battery -ve is 00.2 ohms on my multimeter, that's basically the same as between the battery and chassis, or battery and engine. The above diagram shows how it's usually wired. In other tests, I have disconnected the wires from the car, + and -, then run new temporary wires to the gauge to ensure they're separate. It'll start if i do that AND the O2 sensor is unplugged from the gauge. If the sensor is plugged in, we're back to no start. The 02 does get hot when it's plugged in. The ECU appears to be grounded through its plug, and the ECU case seems also to be ground. I can't easily see where the plug wires then go as they're all bound up and I have no diagram, so I'm hoping someone knows of tests I can do such as the voltage drop you mention. From speaking to others, I hear that a big enough drop will upset the ECU, but that was in the context of a bad starter pulling lots of current. When i read the battery voltage during cranking, it goes from 12.3 down to 10 and a bit. Then back up to 13.4 ish when running. With the AF connected, it does the same, except it won't start. Thanks

Hi, all This is the ongoing issue I've mentioned in the hard starting thread, and a few others, but I wanted to share what's up in case anyone who's good at electrics can help. It's confusing the hell out of me, but I'm no auto electrician. The headline is that when I connect my AF gauge or something like a USB socket in the manner described in the diagram, it seems to upset the ECU and the car won't start. From measuring and logging, the RPM data disappears from the logs using my SCT device, and the Fuel pump driver module stops sending 8v to the pump, as normally commanded by the ECU. The problem comes when the AF is powered and the earth is in any way connected to the chassis earth. As soon as I disconnect the device, the car starts and runs well. The rewiring I've done to see what happens is You'll see from the diagram that the wiring is about as simple as it gets. +ve from the battery, -ve from the chassis but this setup results in no start. If i run an earth from the battery to the earth bolt (in diagram) or even directly to the AF gauge negative wire - no start if i get a spare battery and connect - and + to the gauge with the O2 sensor connected - no start Connect a spare battery to the AF gauge and DISCONNECT the O2 sensor - START Connect the car's battery to the AF and DISCONNECT the O2 sensor - START So... to me it seems like an earth issue, but I don't know what or how to test. I can tell that the ECU's case is earthed, that the engine, chassis and battery have very low resistance between any of them. The Battery to engine wire is new, the battery is new, but now I'm stuck. I don't have a wiring diagram and without taking out the dash and un-bundling the loom, i can't easily trace wires. I do have the Focus green book which shows me ECU pins and their connections. If anyone has any thoughts on what's going on here, I'd love to hear them! Otherwise the car is great. It goes like a scolded cat and has made me into a minor celebrity in the neighborhood Thanks in advance http://www.usa7s.net/vb/attachment.php?attachmentid=13616&stc=1

Just to add an update to my hard starting issue on my 05 SVT car. For some reason, if i attach something that draws power before the car starts, such as an accessory socket and charger for my cell phone, or my new wideband A/F gauge, i get trouble. At first i thought i had used a positive wire meant for something else and upset the ECU, but upon rewiring the device between a new positive wire from the battery, and what appears to be a factory earth point (already has several earths from the loom connected to it) it stops the car starting. I haven't done anything else to investigate yet, but the symptoms are that it cranks-fires-dies ad infinitum. I also measured the voltage between the FPDM and the fuel pump which should start at 6v upon ignition, then go to 6-8v when the engine fires but during this weird non-starting condition, the ignition 6v comes and goes as it should, but the 8v to keep the motor running vanishes. During logging there were some other ECU data points missing such as RPM, cam position and a few others, but the whole thing meant i was going nowhere. I have no idea why this would happen. my only thought is that somehow the devices are interfering with the PATS under the dash since they're close to each other, or there's an earthing issue somewhere. I'll report back if i solve it.

Thanks, Breezy I have the Zetec supplement, but you're right, it does not contain any additional wiring info so I only have the standard stuff.

Hi, folks i'm looking for a wiring diagram for my 2005 zetec SVT engine'd car. I have the build manual, but the diagrams are for the K-Series motor. I've asked Caterham to no avail. Thanks in advance

Mine were rotted so i took the originals to the auto parts store, and they let me root around their racks until i found ones that matched.

Hi, all my woes continue on my 2005 SVT Zetec motor car. It's been in the shop for 3 weeks having its ECU reprogrammed, but it remains extremely hard to start, if it starts at all. In an effort to do something that might help (aka clutching at straws) I started checking wiring and connections in case i can see anything amiss. There's a red cable with a ring terminal labelled 'alternator' that is currently connected to nothing. It's scratched like it was once connected, I think it belongs on the terminal that connects the thick red cable between the battery and the alternator, but I can't tell. Has anyone seen this before and can point me in the right direction? I don't have a wiring diagram to help. http://www.usa7s.net/vb/attachment.php?attachmentid=13404&stc=1

i took my car to a ford performance mechanic. His solution to my hard-starting issue was to add a fuel check valve. I think there's meant to be one in the fuel pump, but if so it appears to have failed, so he added another in line to keep the fuel pressure in the rail and available when starting.

Same here. I still want to drive a seven under a car park's barrier as show in the intro to the very first episode. My friend and I used to watch the intro again and again to see the Lotus

Hi, Slomove That's a good idea and I have checked with Megasquirt about that. The problem for me at least, is that they say their ECU is not for road cars and mine has to go through emissions, which means an OBD read every year and a MIL must be present and functional on the dash. I think this would work for owners who don't have to jump this hoop, or have older cars that are exempt.

I'm also getting the hard-to-start problem with my 2005 SVT motor car. It can take over a minute of cranking, over several attempts, to start. usually it'll fire perhaps one cylinder for a bit until it eventually starts. After that, it runs pretty well. Anyone find any solutions?

Thanks, guys That's all interesting information. Tom and I have been in contact. I'm waiting for the car back from the mechanic's to see what issues he finds. As a note, i changed the fuel pressure sensor on the car at the weekend and nothing really changed in terms of PSI reading on my scanner, but when it failed to start this morning for a minute or so, it appears to have logged a code pertaining to fuel pressure sensor high output (that's from memory as i only saw it briefly at the mechanic's place) so perhaps the pump is not performing as well as it might, or perhaps something's up with the FPCM as Breezy points out. Thanks again

I spoke again with the GCAF (Ga. Clean Air Force) guy. He said he believes one system on the car can be 'not ready' and it will still pass. I also spoke to a mechanic who thought the same. He's going to see the car today so I should have some more information in a couple of days.

So just an update for anyone interested now or in the future. I met with a GA clean air force guy who was very helpful and confident that i'd be able get an exemption for this unusual car and all looked on the up! Until today when he said that that won't happen, and that I have to get the car repaired, and by repaired he means modified since there's nothing wrong with it. Any by modified, he means it has to have the codes removed from the ECU and a MIL physically installed so that it lights up on ignition, or with any DTCs Advice to anyone thinking of getting a post 1996 registered Caterham in one of the 13 emissions counties in GA; change one of those factors. Get one that's registered as an old Lotus7, register it somewhere outside of the 13 counties, out of state, or find someone talented at car electronics to nix the codes, make it test-ready and add the idiot-light to the dash. Right now I'm getting very low on ideas. I think I will have to register it (and pay more tax) in NC to get around this. They allow a car stored in NC to be registered there if you have a house, or a contract showing you're renting a space, garage or similar.

Thanks, 1turbofocus That's interesting, thanks for coming back to me. I might be interested in that. It might save me a lot of messing about if i can't get exemption from the GA clean air force.

Thanks, Kitcat, I'll keep that in mind. Today I got under the car whilst my wife put on the ignition and I could hear the fuel pump run briefly. I also changed the fuel pressure switch and found pressure in the rail. The change made no difference so it seems that that 0psi reading is perhaps not related to my setup. whilst i was in the mood, i changed the coil pack but i still get the odd slow-to-start problem. In fairness, the car has done only about 170 miles since 2012 so when I finally get plates, i'll take it on a longer drive, feed it some injector cleaner, and see what shakes out. Currently i'm only able to take it round the block. One unrelated thing I've noticed about these cars is that they really get a lot of attention! I should have expected it, but i'm new here Thanks again