Author |
Message |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8
Posts: 1015 Reg: 02-2010
| Why does my V8 have to have more than one go to start and stumble up for a second till it purrs? Once it has run it starts every time first up but when it has sat till cold/overnight it never starts first up. When I did compression it was 180 on all cylinders. Plugs and coils are good. Rotors were changed ages ago but it was still a problem then. Could it be the distributor caps, have't checked them in ages? Igniters are good. Leeds are good. I tried a different fuel pump, higher pressure and that did not make any difference. I have one thought??? The car uses power steering oil and there are no leaks under the car or from the hoses, so guess that valve that has something to do with fast idle when you pull lock on may be leaking power steering fluid into the cylinders overnight. Could this be it? How to check? How to fix inexpensively? Thanks for any help Cheers John |
Tom Richards
Goo Roo nsw V8
Posts: 2250 Reg: 08-2005
| disconnect the hoses and block off with a screw and see what happens. |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8
Posts: 1016 Reg: 02-2010
| I thought you might respond Tom And I thought that might be the answer too. Do you know where the post is that talks about this? It was all I could think of. I read it years ago and am not sure where to look. Cheers John |
Tom Richards
Goo Roo nsw V8
Posts: 2251 Reg: 08-2005
| dont know where the post is. check if there is oil in the line from the PS to the throttle body |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8
Posts: 1017 Reg: 02-2010
| Hi Tom, I discovered the valve assembly, and yes, there was oil in the back outlet which goes to the plenum, so I blocked both ends. I left the other one that goes to the air "T" on the plastic air intake pipe as it was dry. We will see now if it makes any difference? |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1021 Reg: 02-2010
| It made no difference, except to say that it seems to have stopped me using power steering oil, at least it looks that way. I will see in another few thousand kilometers if that continues to be the case. BUT It is still hard starting. Like one attempt at starting on first pop will acheive nothing but after the fuel pump tries to establish its pressure head the second or third go kicks it into life. I stumbles at first but then it is away. The higher pressure walbro pump does't fix it either. What next?? |
Daniel Bonnor
Tinkerer Queensland soarer uuz31
Posts: 28 Reg: 06-2014
| have you had the battery checked john? i had some funky starting starting problems from a dead cell once |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1022 Reg: 02-2010
| Battery is a new red top ultima glass matt, fabulous battery (can buy direct on ebay for the great price of $250). More suggestions? |
Dan Newton
Tinkerer Qld UZZ31 V8
Posts: 20 Reg: 09-2015
| Have you checked your coolant temperature sensor? I had the same prob on my Caldina. The temp sensor was faulty and on a cold start the car farted and coughed because the sensor was telling the ecu it was already warm. On a cold start a rich mixture is required so car was under-fuelling but eventually fired. However, on a warm start it purred straight away. Easy and cheap to replace, could be worth a shot. |
Brett Harrison
DieHard QLD JZZ30
Posts: 949 Reg: 09-2005
| The coolant temp sensor is likely the one for the cold start injector on a first gen 1uzfe. fuel pump ecu ? |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1023 Reg: 02-2010
| Hi Brett, Are you referring to the one just on top of the thermostat housing, it is green, or the one at the bottom of the radiator? I am pretty sure that I changed the one on the top of this car, I remember changing the top one on my 32 when I had it. |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1024 Reg: 02-2010
| Thanks for your input Dan. Brett, I had a problem with the fuel pump ecu connection that took me a year to find. I shifted the ecu to the boot and cleaned the connections and it fixed a miss/dieing that I had when it only gave me 8 volts instead of the 12 volts that are needed on start up or heavy acceleration. |
Dan Newton
Tinkerer Qld UZZ31 V8
Posts: 21 Reg: 09-2015
| Seems unlikely that it would be the fuel pump ecu. Easy way to find out is bridge pins B+ and FP in the diagnostics port. This puts 12v straight to the fuel pump when the ignition is on. If it starts fine then the fuel pump ecu is probably shagged, if it makes no difference then you need to look elsewhere. I wouldn't recommend you leave it bridged if it is the problem though, as the diagnostic port isn't rated to carry the fuel pumps electrical load and also the ecu won't shut off fuel in an accident without the FP ecu's monitoring. |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1025 Reg: 02-2010
| There are 3 sensors near the thermostat housing in the picture attached. Can anyone explain what the other 2 are for? There is also the one at the bottom for the radiator (I think that is for the fan?) |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1026 Reg: 02-2010
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Dan Newton
Tinkerer Qld UZZ31 V8
Posts: 22 Reg: 09-2015
| 1 is the coolant temp sensor for the ecu, 2 is the cold start injector time switch, which operates when coolant is below 22 degrees Celsius and 3 is the sensor for the temp gauge. |
Dan Newton
Tinkerer Qld UZZ31 V8
Posts: 23 Reg: 09-2015
| Perhaps #2 sensor might be playing up and the cold start injector isn't operating. Oh and you're correct, the other one operates the fan. |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1027 Reg: 02-2010
| Thanks Dan, #2 looks like the one that I need. Now how to order such a creature? I will start by seeing if someone has one second hand on here. |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1029 Reg: 02-2010
| I have a cold start time sensor coming to me but now I have a different problem, but maybe just the next stage of the failure of the cold start sensor? The problem is that today as I coasted, in auto of course, up to the lights the car stalled and would not restart without giving it throttle and holding the revs above 700. If I do not do that then it stalls again. I can keep it running ok if I am aware of the revs but such a condition is unacceptable. I did change a throttle position sensor about 20,000 klms ago, not long, so that should not be the issue. I reconnected the power steering vacuum line that I had blocked up, just incase that was it but that did not make any difference. I have read in the past of people experiencing stalling problems but a quick search did not reveal anything. Who can give me the clue to what to do next? Cheers and thanks ahead of time. |
John Street
DieHard NSW .91 V8 , 2015 VW Jetta TDI, 2009 Saab 9-3 Turbo
Posts: 547 Reg: 08-2005
| Have you had a look inside your main ECU , leaking caps seem to be the cause of most problems these days |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1030 Reg: 02-2010
| Thanks John, I will have a look at the main ecu after I put the cold start sensor in and bridge out the fuel ecu, probably mid week. I had my main ecu fully recapped about 50,000 klms or 5 years ago, so should not be that. |
Scott Vim
Goo Roo Vic Soarer (1uz) Chaser (1jz)
Posts: 1590 Reg: 12-2010
| It will be one of the things you replaced recently. I've been thrown off by this kind of thing before. Ruling out the obvious things because I fixed it only a couple of years prior. Look at the most obvious things first even if you only just replaced that item. I had a coil go bad again and I wasted time checking other stuff thinking it couldn't be that coil I had replaced recently. |
John Stafford
Goo Roo Qld. Soarer UZZ31 GT-L V8, limited edition Subaru WRX
Posts: 1031 Reg: 02-2010
| Found it!! After bridging between FP + B and confirming that it was not the fuel pump ecu I looked further on the net and discovered an article that I read when I first got my soarer. It was about the idle mixture control on the front of the motor near the thermostat, . Peter Scott did a write up on what is called the IAT sensor, which affects the idle, sometimes causing stalling or hunting sending the idle from excessively low rpm. to as high as maybe 2000 rpm. I took the IAT out (a 15 minute job) and cleaned the end, which gets carbon build up, stopping the moving part from seating in the hole that it fills in the plenum. Once I had cleaned the end I put it back. There was no difference when I put it back. BUT: When I woke in the morning I felt to take it out again and to test it further and found that the shaft, that is supposed to come in and out of a magnetic field like a window winder motor, was jamming, so that it did not go in and come out freely. I freed it up and lubed it with Lenox and put it back to see if I had found the problem. At first it was erratic but as Peter Scott said, eventually the ECU and this sensor managed to talk to each other and all is cured. Powdered graphite is recommended to stop it sticking but I did not have any of that. I will know what to do if it sticks again in the future. Relief. thanks for being a part of this journey. Cheers John |
Roland Elliott
TryHard New South Wales uzz32 1uz-fe
Posts: 174 Reg: 08-2014
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John Stafford wrote on Monday, April 18, 2016 - 06:44 pm:
The IAC has 2 bearings , they are common sizes and easy to replace , they foul up with age causing idle problems, some grease and a clean will solve the problem. |
Brett Harrison
DieHard QLD JZZ30
Posts: 950 Reg: 09-2005
| John, IACV or IAT. IACV is what you are describing. IAT, is located on AFM, effects fuel and ignition tables, amongst others, but also unlikely to cause hard starting. |