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View Full Version : Odd behavior during tuneup with TE1/E1



sefiro
06-14-2014, 11:20 AM
91 GT 5SFE, 300K with full rebuild in 2014.

When doing tuneups on this vehicle, I would connect TE1/E1 per the instructions. Normally, the engine would increase RPM's for a few seconds and then drop to a RPM level less than what I had started at. I would set idle, timing, pull the TE1/E1 connector and have the rpms return to normal.

This weekend, while trying to research some weird hesitation problem, I found the tuneup behavior changed, When connecting TE1/E1 - the rpms would increase per normal, but instead of dropping to less than normal, they would return to normal. I was able to confirm that the rest of the TE1/E1 behaviors were working correctly - namely - a) the advance on timin would stop allowing for correct timing and b) the check engine lite would flash correctly.

Any ideas?

Does anyone know what are the actual list of items/behaviors are that should be invoked when connecting TE1/E1. For eg, I found elsewhere in the FSM that this connection would cause the VSV for the EGR system to turn on.

sefiro
06-23-2014, 08:02 AM
May have found the problem,

Car was idling at around 1000rpms. Idle screwed turned all the way in. Prior to symptoms, the car would idle around 750 per FSM and still have 2-3 turns available.

1) Went through all of the vacuum hoses attached to the manifold and determined that none of them were open. Checked by hooking up tach to system, took a reading in idle, pulled each hose and plugged the manifold opening and compared the resulting tach reading. Verified that all devices were off.

2) I've been searching for a solution for a misfire at high rpms. Had been testing all of the attached sensors etc. Found that the throttle opener (vacuum controlled) was mis-adjusted. It was reading about 2000rpms and had to be adjusted down to the 1300-1500RPMS. That also brought down the normal idle to about 850.

3) Also was chasing an odd noise that was occcurring during fast acceleration - sounded like high pitched flapping (throttle?). Found that the hose connecting the EGR modulator to the EGR was split. Replaced the hose which silenced the noise and also brought the idle down to 600. Was able to adjust the idle to 750 and still have turns on the idle screw availble.

Question: I had previously tested the EGR modulator and EGR vacuum ports and found they were all responding per the FSM. The hose connecting the EGR modulator to the EGR is connected to ports on these devices that are not connected to the intake manifold. The hose appears to carry exhaust backpressure to the EGR modulator to enable the control of the EGR. Why would not having the hose installed cause the RPM's to rise just like an open vacuum port?

MCcelica
06-23-2014, 06:22 PM
When I read your first post, I'll admit that I hadn't heard anything even remotely like that before. So glad you found it. I'm afraid I still don't have an answer for your question, though.