Supra510

Searched quite a bit on this and the threads I've found end without an answer. I have a 1992 SC400. A few days before this happened I noticed it would kind of cut out once in a while going down the freeway, but it always kept going.

I've completed the 12V fuel pump bypass and I can hear the pump come on when I turn on the key. The car will start every time. But then it dies immediately. It won't stay going long enough to even rev it and it died while cruising down the road so I don't think it's related to the IAC valve.

Any ideas?

ZPEED

throttle sensor

LEX_MAN

iTrader: (2)

AFM maybe?

Klaus

iTrader: (1)

Pull your codes- open the diagnostic port in your engine bay and run a small wire between the TE1 and E1 terminals. Turn your key to the on position and count the numbers.

Compare with these codes:
12 - RPM signal no. 1

13 - RPM signal no. 2

14 - Ignition no. 1 signal

15 - Ignition no. 2 signal

16 - ECT control signal

17 - No. 1 cam position sensor signal

18 - No. 2 cam position sensor signal

21 - Main oxygen sensor signal (on left bank)

22 - Water temp sensor signal

24 - Intake air temp. sensor signal

25 - Air-fuel ratio lean malfunction

26 - Air-fuel ratio rich malfunction

27 - Sub-oxygen sensor signal (on left bank)

28 - Main oxygen sensor signal (on right bank)

29 - Sub-oxygen sensor signal (on right bank)

31 - Air flow meter signal

35 - HAC sensor signal

41 - Throttle position sensor signal

43 - Starter signal

47 - Sub-throttle position sensor signal

51 - Switch condition signal

52 - No. 1 knock sensor signal

53 - Knock control signal

55 - No. 2 knock sensor signal

71 - EGR system malfunction


Let me know what you find. Having identical problem. I have Code 15. I have replaced both of my igniters, replaced spark plugs and wires, tried a new ECU, replaced my MAF, and I am going to replace my coil packs this week. Interested to see what you come up with.

Klaus

iTrader: (1)

I'll tell you as well that I have been hunting this problem for 6 months. CL hasn't really been any help, just shots in the dark. ID your codes, and then go from there.

Chin

iTrader: (34)

I was working on a 1994 LS400 today with a similar problem. Even though the car I am not working on is not completely fixed, this is what I found. The ignition fuse was loose in the fuse box therefore not powering up the ECU. You can tell the ECU is not getting power by turning your ignition on, if the check engine light does not illuminate with the other lights, it's not getting power. By pressing on the ignition fuse with my finger while it was still in the fuse box, I was able to get consistent power and the car started up perfectly every time. It's worth a shot. Also pull the fuse and check for corrosion or just replace the fuse with a new one. I slightly bent the blades of the fuse in opposite directions so it would fit more snug in the fuse panel.

Klaus

iTrader: (1)

^would this car sometimes start and run perfectly for 5-30 minutes then die again and unable to restart again for 30 minutes to a day? I'll look at that

Chin

iTrader: (34)

Give it a shot, it costs you nothing and takes a few minutes. Jest keep an eye on your check engine light and make sure it's on when you turn your ignition on. The ignition fuse in the LS400 was a 10amp, not sure about your car.

Klaus

iTrader: (1)

Also my ECU is throwing a code for one of the ignition banks when it's failing- code 15. What codes was the LS giving?

Chin

iTrader: (34)

Code 13 or 14. Can't remember, it was too hot outside today. The ignition relay was not energizing under the hood until I found the problem with the loose fuse. I thought the previous owner was shady and pulled the check engine light bulb, but it was because the ECU was not getting power. The car now starts and runs perfectly if I bypass the fuel pump ecu, but the thing is I have 2 spare junkyard fuel pump ecu's and I am wondering if all of them are bad? Seems unlikely but...

I am trying to see if there is a bench test I can perform on the fuel pump ecu's so I do not have to do the bypass.

njsc3000

tps or iac if u get an engine light troubleshoot it..

Klaus

iTrader: (1)

All speculation until he pulls his codes- an IAC or TPS would not cause this, and mine are tested and functioning perfectly.

Enigma8246

I had this problem and replaced the IAC from research on here. I continued to have the same problem and called a friend of mine who is a service rep at the local dealership. He put the shop manager on the phone with me and he told me that it is due to a weak connection with the battery and if you momentarily lose contact to the battery while driving and regain it (ie cutting off on the highway and coming back on) sometimes your IAC will not reset properly. Disconnect your battery for a while to reset your ECU and IAC, reconnect your battery making sure to tighten your terminals properly and try it again. It worked for me and i wound up having to move my contacts for my HID kit because it was causing the terminal bolt to loosen from vibration resulting in this problem. Also, make sure your battery bracket is securely fastened.

Edit: Klaus, I don't remember if I was throwing any codes with this issue, but I do remember I tested my IAC per the manual and it was passing.

Klaus

iTrader: (1)

Again we need more info- if just the engine dies it's unrelated to the battery. I finally solved my problem- I assumed the the "new" coil packs installed on my car when I bought it were properly done- turns out they were some cheap "made in china" coil packs and my passenger side one obviously fried out. When I replaced them with proper OEM denso ones the car fired up and drove perfect for 2 hours.

OP we need the following info:
Codes
Does just the engine cut out, or all of the electronics too.

Supra510

Thanks for all the replies. More good info in this thread than most others combined. I'll check codes and try the other fixes as well. Thanks for the help.