mawby Posted August 2, 2009 Share Posted August 2, 2009 My MR2 developed an interesting problem today. It started but stalled. It started again but was idling rough and the engine fault light was on. So I turned it off and tried to read the error code but I wasn't able to, the engine light wouldn't flash like it should do - even to report no error. Whilst trying to diagnose the problem I was stood next to the engine bay talking to someone whilst the ignition was on, probably for about five minutes, when all of a sudden there was a click from the engine bay. I then tried starting the engine again and it was working fine, and the engine warning light went out. I then tried reading the error code again and this time it worked although it unhelpfully had no error code stored! So I took it for a very quick drive to get some petrol, and upon restarting it at the petrol station the problem happened again. I managed to drive it home but the car was in some kind of limp mode with the auto box staying in 3rd and the engine not wanting to rev over 4k rpm. So I got it home and started to look at what could make the clicking noise. After some trial and error I managed to find the culprit, I think, but I'm not sure how to fix it. This little device is what I heard making the click noise before it started working. It appears that when the ignition is off the valve (I'm assuming it's a vale of some kind) is closed, but when the ignition is turned on the valve swings open. However, when it was having a problem this valve wasn't opening when the ignition was turned on. I tried wedging it open and starting the car but that made no difference, so I'm assuming it's not this valve at fault but whatever controls it. So, can anyone confirm exactly what this device is, what controls it and what the likely cause of the problem is? Quote Link to comment Share on other sites More sharing options...
mawby Posted August 3, 2009 Author Share Posted August 3, 2009 No one? A bit of investigating and I think this is part of the EGR system. Although that document is for a 3S-GTE and isn't exactly the same. Quote Link to comment Share on other sites More sharing options...
shima60 Posted August 3, 2009 Share Posted August 3, 2009 i say cable tie the valve open see if that helps. just looks like an air bypass valve. (i could be wrong) Quote Link to comment Share on other sites More sharing options...
mawby Posted August 3, 2009 Author Share Posted August 3, 2009 i say cable tie the valve open see if that helps. just looks like an air bypass valve. (i could be wrong) I did try that but... I tried wedging it open and starting the car but that made no difference, so I'm assuming it's not this valve at fault but whatever controls it. Quote Link to comment Share on other sites More sharing options...
shima60 Posted August 3, 2009 Share Posted August 3, 2009 ah sorry should have read the thred properly. you tried blowing out your vacuum pipes and checking there all connected? Quote Link to comment Share on other sites More sharing options...
mawby Posted August 3, 2009 Author Share Posted August 3, 2009 I haven't, but I don't think it's a pipe issue because it works after a while, and in fact worked first time this morning with no problems. Having found that link above I'm guessing it's a sticky VSV or a dodgy wire to it. Quote Link to comment Share on other sites More sharing options...
Lazarus Posted August 4, 2009 Share Posted August 4, 2009 The valve you've shown is part of the Acoustic Control Induction System (ACIS), this is supposed to control unwanted pressure pulses within the inlet tract, which causes, amongst other things, rough running. It's vacuum controlled from a VSV so my first thought would be a vacuum problem. If it was a VSV signal/electrical problem I would have expected to see an ECU fault code. It could still be the valve thats at fault, maybe the valves diaphagm is split. See if your celica has the same valve (it has the same engine) and substitute it to see. Quote Link to comment Share on other sites More sharing options...
jevansio Posted August 4, 2009 Share Posted August 4, 2009 Isn't the ACIS a very crude form of VVTI? Quote Link to comment Share on other sites More sharing options...
Lazarus Posted August 4, 2009 Share Posted August 4, 2009 (edited) Isn't the ACIS a very crude form of VVTI? Sort of... "Acoustic Control Induction System, or ACIS, is an implementation of a Variable Length Intake Manifold system designed by Toyota. Simply put, the ACIS system uses a single intake air control valve located in the intake to vary the length of the intake tract in order to optimize power and torque, as well as provide better fuel efficiency and reduce intake "roar".[1]. The ECU controls the position of the intake air control valve based on input signals from throttle angle and engine RPM. The vacuum switching valve (VSV) which controls the vacuum supply to the actuator is normally closed and passes vacuum to the actuator when it is energized by the ECU. By energizing the VSV vacuum is passed to the actuator, closing the air control valve. This effectively lengthens the intake manifold run. By de-energizing the VSV, vacuum to the actuator is blocked and trapped vacuum is bled off of the actuator diaphragm. Toyota ACIS is an On/Off system. The valve (or valves in newer models with multiple valves to create more than 2 lengths) is either fully opened or fully closed. An example of early single valve ACIS programming would be the 3.0L 3vz-fe engine. The ECU actuates the vsv to close the valve at a TPS (throttle position sensor) input of 60% or greater AND 3,900rpm or greater. ACIS is NOT a gradual system." The ACIS system doesn't "create" more power/torque, it is an attempt at making a variable pulse tuned intake so the engine will run more within a wider optimal rev band. Edited August 4, 2009 by Lazarus more words (see edit history) Quote Link to comment Share on other sites More sharing options...
mawby Posted August 4, 2009 Author Share Posted August 4, 2009 Having looked at the diagram attached it shows the only thing that could 'click' and then make this work is the ACIS VSV, which I found tonight near the bottom rear of the engine in an awkward place to reach, only rivalled by a Rover's ignition coil! Would you expect the ACIS to be able to cause such a problem if it failed to open (or close - I can't work out which way around it is!) when the engine starts? It also seems strange that me forcing it open/closed didn't cure the problem. I hope it's not an ECU problem! That would be just my luck. Quote Link to comment Share on other sites More sharing options...
Nodalmighty Posted August 5, 2009 Share Posted August 5, 2009 Would you expect the ACIS to be able to cause such a problem if it failed to open (or close - I can't work out which way around it is!) when the engine starts? It also seems strange that me forcing it open/closed didn't cure the problem. I hope it's not an ECU problem! That would be just my luck. It won't be the ACIS causing you these problems. It fails open, however, they are known for the screws coming lose and the butterflys dropping into the inlet ports. Take the lid off and have a goose. Sounds like you have a relay in the rear fuse box which is on it's last legs, that will be the click you heard. They are Fan (Round), Ignition/igniter (Grey one), Injectors (other round one), Fuel Pump/ Circuit opening relay (big black one). Check the IG2 7.5amp fuse hasn't blown as this kills the O2 sensor, idle control valve, alternator and various vsv 12v feeds. Lyndon. Quote Link to comment Share on other sites More sharing options...
mawby Posted August 5, 2009 Author Share Posted August 5, 2009 Although I don't understand him, being able to see inside the ACIS has helped me understand how it works. 9fYDd94pf98 I checked all the fuses and they were fine. If it was any of those relays (excluding the fan) I wouldn't have thought the car would start at all? It's a pain the ECU isn't storing an error code to give me a clue. Quote Link to comment Share on other sites More sharing options...
Nodalmighty Posted August 5, 2009 Share Posted August 5, 2009 Although I don't understand him, being able to see inside the ACIS has helped me understand how it works. 9fYDd94pf98 I checked all the fuses and they were fine. If it was any of those relays (excluding the fan) I wouldn't have thought the car would start at all? It's a pain the ECU isn't storing an error code to give me a clue. The big black one takes a feed from both the start signal and the ECU so it can run to start the car but stop soon after if the ECU doesn't keep it alive. The biggest cause of random issues with MR2 are grounds. Check all of them (Especially the smaller spider grounds as these can cause all sort of randomness) for tightness and corrosion. Also check the ECU grounds under the inlet manifold as these to can cause no end of strangeness if they are not tight. Lyndon. Quote Link to comment Share on other sites More sharing options...
mawby Posted August 5, 2009 Author Share Posted August 5, 2009 I had a look tonight for bad earths but I didn't find any. (I didn't really find that many though so maybe I missed some) I did unplug and plug back in every connector in the engine I could find. I checked the main wiring loom from the ECU as there is a break in the protecting cover at the point it passes from the boot to the engine bay, but I couldn't see any damaged wires. I did notice that whilst the ignition was on for a long time all of the relays you mentioned above got very hot, except the circuit opening relay which at best got slightly warm. I'm hoping this means this relay is duff. I have the test procedure for this relay from the Toyota workshop manual so I'm going to give that a go tomorrow and see what happens. Quote Link to comment Share on other sites More sharing options...
Nodalmighty Posted August 6, 2009 Share Posted August 6, 2009 I had a look tonight for bad earths but I didn't find any. (I didn't really find that many though so maybe I missed some) I did unplug and plug back in every connector in the engine I could find. I checked the main wiring loom from the ECU as there is a break in the protecting cover at the point it passes from the boot to the engine bay, but I couldn't see any damaged wires. I did notice that whilst the ignition was on for a long time all of the relays you mentioned above got very hot, except the circuit opening relay which at best got slightly warm. I'm hoping this means this relay is duff. I have the test procedure for this relay from the Toyota workshop manual so I'm going to give that a go tomorrow and see what happens. If all else fails contact Rogue MotorSport, Patrick has just about every MR2 ecu and electrical relay ever made so he would be able to do swap tests for you. Lyndon. Quote Link to comment Share on other sites More sharing options...
johnny g Posted August 6, 2009 Share Posted August 6, 2009 If all else fails contact Rogue MotorSport, Patrick has just about every MR2 ecu and electrical relay ever made so he would be able to do swap tests for you. Lyndon. Or Woodsport Quote Link to comment Share on other sites More sharing options...
mawby Posted August 6, 2009 Author Share Posted August 6, 2009 Woodsport are too far away, even Rouge Motorsport are close to 100 miles away from me. I really need this to be something I can fix myself as this is supposed to be a cheap run-a-round and I can't afford to take it to a garage at the moment. Quote Link to comment Share on other sites More sharing options...
mawby Posted August 6, 2009 Author Share Posted August 6, 2009 Well then, I think I'm getting closer to the problem. First thing tested tonight, the open circuit relay... Test 1: Result: PASS Test 2: Result: PASS Test 3: Result: PASS No problems found there, you could hear the relay clicking on and off, so next I checked the the diagnostic port... Test 1: +B voltage Value: ~12V Result: PASS Test 2: +B to FP continuity Result: FAIL Ah ha, so I know the relay works but I now know the relay definitely isn't being activated, so next I moved on to the connectors to the relay... Test 1: +B voltage Value: ~12V Result: PASS Test 2: E1 to bodywork continuity Result: PASS Test 3: FC to bodywork continuity Result: UNKNOWN - I'm not sure if this should be earthed with just the ignition on or whether it will earth once the relay has opened. For the moment I'm assuming this is a PASS, but if anyone knows for sure let me know. Test 4: STA voltage Value: ~1V Result: UNKNOWN - I have a sneaky suspicion that this is the problem. There is definitely voltage there but I don't think ~1V is enough to activate this relay, so for the moment I'm assuming this test is a FAIL. Now all I need is for the relay to 'work' so I can pull it out and repeat tests 3 and 4 to confirm which is the problem, but I'm 99% sure it's the power from the ignition switch (ST2) that's the problem, especially given that... 1) I have recently had the dash apart, 2) Whilst apart I commented to Tigger about how shite the wiring was for the alarm/immobiliser! So it's time to go back to the workshop manual and see if it tells me what voltage ST2 should be reading. Quote Link to comment Share on other sites More sharing options...
mawby Posted August 6, 2009 Author Share Posted August 6, 2009 Ah bugger. ST2 is when the ignition is cranking, so there probably shouldn't be any voltage present with just the ignition on. So maybe it is FC at fault. Quote Link to comment Share on other sites More sharing options...
Nodalmighty Posted August 7, 2009 Share Posted August 7, 2009 (edited) Ah bugger. ST2 is when the ignition is cranking, so there probably shouldn't be any voltage present with just the ignition on. So maybe it is FC at fault. If you suspect the Fuel Circuit, Bridge FP & B+ in the diagnostic port and see if the fuel pump runs with the ignition on. If it does, try and start it and see if it runs properly. If it does then there is definitely a problem with the CO relay of FC from the ECU to the CO relay. If you De-Pin FC from the ECU connector and force it to ground the fuel pump should run, if it doesn't you have a wiring fault. Check you have voltage to the injectors, coil and ignitor (Black/Orange or Black Red wires). The igniter grounds though the body of the unit so make sure the bolts and screws look in good order. Check the coil unit isn't cracked (quite common). Have you pulled the Dizzy apart and checked the rotor arm hasn't broke or something daft? I'm going to Rogue to MAP their Brit Car tonight if you want me to get you some bits. Lyndon. Edited August 7, 2009 by Nodalmighty (see edit history) Quote Link to comment Share on other sites More sharing options...
mawby Posted August 7, 2009 Author Share Posted August 7, 2009 The cap and arm are new. This is an intermittent problem (although more broke now than not!) so if something was physically broken I wouldn't expect it to work at all. I was considering whether to short FC direct to ground to see if that was the problem so I'm glad someone else has also suggested it too. I'll bridge FP & B+ first though and see if that helps. This is definitely sounding more and more like a short somewhere. Thanks for your help Lyndon! Quote Link to comment Share on other sites More sharing options...
mawby Posted August 7, 2009 Author Share Posted August 7, 2009 Ah bugger it. I bridged FP & B+ and it didn't make any difference. I shorted FC to earth at the relay and it didn't make any difference. Looks like I've got no choice now but to put one of the Supra's back on the road and then book the MR2 into a garage - probably Rogue given how helpful their staff are. So far my saving-money-for-wedding plan has cost me more than if I had just kept using the Supra's! Anyway, time for me to head off to Pod in the only car of five that a) works and b) is road legal. Quote Link to comment Share on other sites More sharing options...
johnny g Posted August 7, 2009 Share Posted August 7, 2009 Coolant temperature sender could be a problem? Quote Link to comment Share on other sites More sharing options...
mawby Posted August 11, 2009 Author Share Posted August 11, 2009 Coolant temperature sender could be a problem?I don't think it is. The symptoms are very short-circuit like. I just can't find it. Quote Link to comment Share on other sites More sharing options...
mawby Posted August 16, 2009 Author Share Posted August 16, 2009 Right then, having stripped down everything I had previously touched I still couldn't identify the problem. So, on the advice of Laz, I took the manual ECU out of my Celica (same engine) and put it in the MR2 (automatic) and the car started up straight away! Put the MR2 one back in - failed again. Double checked by putting the Celica ECU back in - worked. So I think that has narrowed down the problem to this little bugger. Unfortunately, when the car was running, I noticed a small puddle appearing under the radiator. A few drops of coolant were leaking from the radiator air drain, so I tried to close the valve tighter and it did turn about 15 degrees but then there was this hissing noise for a few minutes. So it looks like the valve is buggered. I'm hoping some radweld will fix it as I really don't want to have to replace the radiator because of this valve. Quote Link to comment Share on other sites More sharing options...
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