alxns7 Posted May 1, 2015 Share Posted May 1, 2015 (edited) I'm having cold startup issues after changing the intercooler pipework on the car. Basically the car had a FMIC, HKS SSQV. I have replaced most of the parts so the engine bay looks OEM again. Only the boost controller is still on. I haven't touched any of the vacuum lines other than the boost controller ones. The FMIC is now replaced by the OEM pipework and a CW intercooler, and the HKS BOV by the stock bypass valve. Symptoms are, the car cranks and will sometimes fire (but not enough so that it starts). To start it I need to press the pedal. It looks to me that the engine isn't getting any fuel unless the throttle is open. The car has an Apexi SAFC fitted, and a custom FCD. I believe it works like the HKS FCD, but I'm not sure. I think the TPS isn't the issue as the SAFC shows a throttle opening of 0% when closed. The SAFC was reinitialized before the first startup, unfortunately I didn't write the previous settings down, maybe should have. After startup the car idles without any big problem, though the RPM get higher as it warms up (from 800 to 1100 RPM). Once warm the idle fluctuates by a few RPM around 1100, but nothing alarming. Could the custom FCD be the problem? The car is EU spec so has the MAF meter. We've tried different sensor settings on the SAFC without any noticeable difference. It used to start right up before. I have a CW FCD ready to be installed, perhaps this will solve the issue. Any hint would be much appreciated! Thanks Alex Edited May 1, 2015 by alxns7 (see edit history) Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 1, 2015 Author Share Posted May 1, 2015 (edited) Here is the job done. Edited May 1, 2015 by alxns7 (see edit history) Quote Link to comment Share on other sites More sharing options...
Ian C Posted May 2, 2015 Share Posted May 2, 2015 It's probably too much fuel. Opening the throttle lets the engine get enough air in to burn the overfuel. Removing the FCD and the SAFC from the wiring loom entirely would probably be a good start, but you could also try adding or removing fuel with the SAFC at low RPMs to see if that affects the cold start. Try taking out 10% to 20% airflow signal with it, see if that gets it going Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 2, 2015 Author Share Posted May 2, 2015 If it's too much fuel, I should see black smoke coming out right after it fires up shouldn't I? I will check whether it's the case, might have not seen it. I really want to avoid changing the SAFC parameters I think I will remove it at some point, although I like the monitoring feature. I also read it could be a faulty coolant temp sensor, maybe its connector moved when the work was done. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 2, 2015 Share Posted May 2, 2015 Bypass the FCD and see what happens. Hopefully it's faulty and I can sell you a superbly crafted and correctly functioning one for £50 plus VAT Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 2, 2015 Author Share Posted May 2, 2015 That's exactly why I already got one from you Chris Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 2, 2015 Share Posted May 2, 2015 Ah, so you did, if it's mine that's fitted it won't be that I must read all the messages more closely, sorry. I have seen some other FCD's fitted in the signal wire from the air flow meter, and I do not like that method of fuel cut elimination. Be sure to fit my FCD in the MAP sensor signal wire! Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 2, 2015 Author Share Posted May 2, 2015 I'm sure yours is not the problem because I actually haven't got time to fit it yet! The custom FCD from the previous owner is still on it, I believe it works like the HKS ones, which I read could alter the idle settings. The previous owner assured me it's fitted to the MAP sensor. I will let you know next time I check the wiring around the ECU. Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 7, 2015 Author Share Posted May 7, 2015 Ok so after investigating... it turns out it's a Zener diode setup. Does that make any sense? The Zener diode would let flow the current over 3.9V and by pass the MAP signal. We'll see tomorrow if removing the diode solves the cold start issue, but I doubt it. Is there a way to test the diode with a simple multimeter? A first test showed the flow wasn't getting through in any direction. Anyway, I think we will have to check the rest of the wiring as it seems other stuff has been done! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 7, 2015 Share Posted May 7, 2015 (edited) bin it, not a good way to clamp the MAP sensor signal. You need, ideally, a variable power supply, but a resistor and a 9V battery and a multimeter would test it. Put testing Zener diodes into YouTube. This is a good video: Edited May 7, 2015 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 7, 2015 Author Share Posted May 7, 2015 Thanks Chris, yeah I read about it and it's apparently not a very good way, not precise/reliable enough. Will continue diagnosis tomorrow. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 7, 2015 Share Posted May 7, 2015 Next I would remove the FCD and try it, then, if that doesn't help, bypass the SAFC. Go back to no mods to the fuelling until you find the issue. having to open the throttle to cold start suggest too rich a mixture (probably...). Could also be leaky injectors, or a faulty ECU water temp sensor or connection. You didn't disturb either of the two ground terminals to the plenum lower regio did you? Does the engine management warning work on key on, engine off? Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 7, 2015 Author Share Posted May 7, 2015 Yes the engine fault light works (first fix we did actually, dry solder joint). Alright so tomorrow: -start without the zener diode -check engine faults. I believe there is a test mode that allows to check the circuits from scratch, I mean without having to drive the car first? -check ground terminals. Honestly very possible they have corrosion. -bypass the SAFC Temp sensor should be ok. The gauge works (it's the same signal yeah?) and the connector is in place. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 7, 2015 Share Posted May 7, 2015 The gauge sensor has one wire to it, the ecu water temp sensor has 2 wires to it, and they are totally independent of one another, but located physically close together on a TT. Clear any old codes by disconnecting the battery for 10 minutes, run engine for a while and drive car, use a paper clip to see if fresh codes are stored. Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 7, 2015 Author Share Posted May 7, 2015 Thanks for that info, I might have checked the wrong one. The more I read the more I think it should be a faulty coolant temp sensor. We'll look closer to it. We did flush the cooling circuit many times, including flush/cleaning additive. It was VERY rusty. Could the flushes have caused a faulty sensor? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 7, 2015 Share Posted May 7, 2015 Most unlikely, a simple resistance check should show its condition. Figures were provided by Andy Blyth http://www.mkivsupra.net/vbb/showthread.php?238522-2JZ-sensor-resistance! Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 9, 2015 Author Share Posted May 9, 2015 It seems the coolant temp sensor connector wires are only hanging on 2-3 copper wires. Any tip on how to remove the connector without removing the top water hose? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 9, 2015 Share Posted May 9, 2015 I am sure it's possible without removing the top hose, but why not just pop the top hose off it it makes access easier? Toyota can supply termination repair kits, a metal terminal on a short or medium length piece of wire, ready crimped. Just solder to the cut leads to the sensor and put heat shrink tube over the solder joints. I may even have a temp sensor shell in stock, but I won't have the wire ended terminal repair things. Coolant Temp Sensor connector shell: 90980-11062 Wire repair leads with terminals (one wire, you probably need 2 of these) : 82998-12620 Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 9, 2015 Author Share Posted May 9, 2015 Right I guess losing a bit of coolant isn't too bad Can't we use the old connector to repair the wires? Or once locked it stays in position? Not that expensive anyway, but man these terminal repair wires are! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 9, 2015 Share Posted May 9, 2015 If you can get the terminals out without breaking the shell you can re use it. If there's still connectivity to the sensor I doubt this is your problem anyway, the current draw will be tiny. Quote Link to comment Share on other sites More sharing options...
alxns7 Posted May 15, 2015 Author Share Posted May 15, 2015 Ok, a little misunderstanding with my brother, it turns out the sensor does NOT have any connectivity. The wires were torn out of the plug. I ordered new connector and wires, almost sure this should fix the problem. Thanks for your help Chris! Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted May 15, 2015 Share Posted May 15, 2015 Good luck. Sounds promising! Quote Link to comment Share on other sites More sharing options...
alxns7 Posted June 8, 2015 Author Share Posted June 8, 2015 OK so I got to work on the car this weekend, the two temperature sensors were fucked, torn appart, male and female connectors GLUED together. Now why would somebody do this instead of ordering new parts ! Anyway, that's exactly what I did ! Quote Link to comment Share on other sites More sharing options...
Benjy Posted June 8, 2015 Share Posted June 8, 2015 OK so I got to work on the car this weekend, the two temperature sensors were fucked, torn appart, male and female connectors GLUED together. Now why would somebody do this instead of ordering new parts ! Anyway, that's exactly what I did ! Happens more often than you think. I've just fitted a polished water neck and had to order the gauge temp sender plug. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted June 8, 2015 Share Posted June 8, 2015 Merde. C'est la vie! Bon chance mon ami. Quote Link to comment Share on other sites More sharing options...
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