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I am having cold start problems. My mini-starter is about 6 months old and with colder weather the car needs to crank for 10 seconds or more, and may need some throttle blips to start.
After reading Dr. Bob's explanation of voltage drop in my diode Y- connector, I measured the voltage of the yellow wire (from 50 terminal of starter) at the thermo-time switch during cranking to be 9.8 volts while the jump post voltage during cranking is 12.8. The yellow wire connects to the starter solenoid and the cold start valve. My black/yellow wire (also connected at the 50 terminal of the starter) that goes to the resistor/coil circuit will be at least 0.7 volts lower or 9.1 volts.
I wonder if this voltage is low enough at the coil to give me difficult starts?
I am prepared to wire a relay at the starter to duplicate the dual switching function of the OEM starter.
Thanks,
Dave
Last edited by j.kenzie@sbcglobal.net; 11-11-2018 at 10:29 PM.
I’d do the relay. But you knew that. My Honda Pilot DD uses a much more compact SPST relay. I think for space considerations I’d use that one in a shrink-wrap sleeve, mounted with a P clamp on or next to the starter.
Free-market (read: cheap) rebuilds often leave the original solenoid in place. If the aux contact for the ignition isn’t working, the starter may still crank ok but may not fire, especially in cold weather or with lower battery voltage. Add a small relay as described to help avoid the problems.
I’d do the relay. But you knew that. My Honda Pilot DD uses a much more compact SPST relay. I think for space considerations I’d use that one in a shrink-wrap sleeve, mounted with a P clamp on or next to the starter.
Free-market (read: cheap) rebuilds often leave the original solenoid in place. If the aux contact for the ignition isn’t working, the starter may still crank ok but may not fire, especially in cold weather or with lower battery voltage. Add a small relay as described to help avoid the problems.
Thanks Dr. Bob. I ordered the relay, and will install in the week or so. I will report back results.
Dave
I decided to mount the relay in the engine bay where it will be further away from water and heat. I am using the starter signal 50 circuit yellow wire from the thermo-time switch connection to trigger a relay sending 12 volts directly to the 0.4 Ohm resistor in the same place the 16 circuit black/yellow wire from the starter connects. I will leave the starter wiring alone, and just piggyback this relay-switched power. I will fuse the power wire from the jump post to the relay. I can't see why this wouldn't work to restore voltage to the coil resistor circuit during cranking. If you see a problem, please let me know.
Thanks,
Dave
Last edited by j.kenzie@sbcglobal.net; 11-12-2018 at 12:36 PM.
That should work well, since voltage you reported at the jump post is good while cranking. FWIW, you have all the connections you need at the jump post and the 14-pin connector. 50 and 51 in the harness, power at the jump post, and a good ground point forward and below that connector. Get a relay with a mounting tab, socket, and harness and this will be pretty simple.
That should work well, since voltage you reported at the jump post is good while cranking. FWIW, you have all the connections you need at the jump post and the 14-pin connector. 50 and 51 in the harness, power at the jump post, and a good ground point forward and below that connector. Get a relay with a mounting tab, socket, and harness and this will be pretty simple.
Thanks. I ordered a waterproof relay and socket, and will wire it up this week, hopefully.
Dave
Success!! Dr. Bob, you have no business being so smart!
I wired a relay like in my diagram above, and my difficult-to-start car started in about one second!
It stands to reason that Porsche designed a resistor bypass circuit for this model, in order to supply greater voltage to the coil during cranking. The mini starter circuit that is commonly used defeats that purpose, and while it may work under ideal circumstances, in cold weather or lower battery voltage, you might well have starting problems, like I did.
Here is my Difficult cold start thread:
"...This is a new problem. New mini starter 6 months ago which has been working fine. The car has been sitting quite a bit this Summer, and yesterday and today it required about 10 seconds of cranking before it started up. The starter is turning strongly. Once started in runs and drives perfectly. Battery is fully charged.
I was thinking check valve or old gas. Anything else come to mind? (84 US L-jet automatic)..."
Well the newest item was indeed the cause of the new problem.
Thanks,
Dave
Last edited by j.kenzie@sbcglobal.net; 11-17-2018 at 07:20 PM.
Perhaps expert wiring fabricators SeanR and GregB will see fit to add the small relay to their pre-EZx front of engine harnesses. Lots of original and most “common” rebuilt starters can benefit from this simple addition. It really wouldn’t be difficult to add this at the 14-pin end of that harness, and eliminate the 51 wire down to the starter.
Still very happy with this relay setup.
I was worried my success of yesterday might be a fluke, so I went out for a cold start this morning. The car started in less than one second from dead cold. Two days ago, before the relay 50/51 circuit mod, I needed 10 seconds of cranking, and a gas pedal dance to start the car. Huge improvement. I would definitely recommend for 16V non-LH 928's with the mini starter. If I understand Dr. Bob correctly, some OEM starters may not provide full voltage into the resistor/coil circuit, due to solenoid problems.
BTW the relay could probably also be located under the car, near the starter, using the starter main power terminal, the two smaller starter wires, and a chassis ground for relay connections. I did not want to crawl under the car for this, and also wanted to avoid heat and water exposure for the relay and fuse involved. I am happy with my setup, where the relay lives near the jump post.
In retrospect, I probably could have diagnosed my problem, and others could foresee a problem by checking starting voltage at the ballast resistors as in WSM 28-15. That voltage should have been battery voltage, and mine was 9.1 volts.
Thanks again,
Dave
Last edited by j.kenzie@sbcglobal.net; 11-19-2018 at 11:59 AM.
Meanwhile, in other non-relay/diode related mini-starter installations...
I finally got around to installing my IMI-Mini starter today. I wanted to run the starter in the inboard orientation, which meant re-clocking the the mounting plate.
This is how the starter comes from IMI. This is for mounting the starter in the outboard position, closer to the exhaust downpipes/header. This is the orientation for the inboard mounting directly under the oil pan. Thanks to jcorenman for the tip. Notice the orientation of the part number with respect to the solenoid.
Next up I removed the OEM starter and compared the weight with the IMI starter, it's nearly a five pound difference!
And here is the test fit of starter. It took me a while to wrestle with the harness to get the connections to look good. I am not sure I like this set up but not sure how to make it work better. Maybe if I add some spaced to the bottom of that long post it will get the connectors further out. I don't like those exposed nuts and posts, I'd like to have a boot like the on IMI uses to transfer power to the main motor (grey cover). My angle bracket did not come with boots. What are other people using to protect the hot posts?
I didn't get a change to give it a test start. Hopefully tomorrow.
Last edited by Michael Benno; 11-18-2018 at 08:02 PM.
Looks good, Michael. You were one of my inspirations to purchase this starter. It appears your 88 does not have three connections as mine did, so indeed, you don't need to worry about diodes or relays. I think.
Thanks,
Dave
The first try was a bit of a shocker, it made a terrible noice, but I realized it was just the starter gear getting in sync with the flywheel. Second and third starts were fine. You will see some grease spray coming out of the gap on the bell housing. I put some MoS2 grease on the flywheel teeth per the WSM, the excess must be flying off. Pre-condition, the car has been sitting for about a month, it was 40-degress out, and I have 50wt synthetic in the motor.
All in all the starter is a lot quicker than with the original 30-year old starter, which still seemed fairly strong. Here are a couple start attempts after my new exhaust for comparison
I thought I would share this with those of you who have installed or are considering installing the starter. I am curious to know if anyone else has experienced this problem.
I discovered that my IMI Starter was making contact with my front belly pan and was causing some vibrations while starting and while driving in the very specific RPM range of 1600-1800rpm. I was able to verify this by removing the belly pans and no vibrations are present anymore.
On my car, I have the aftermarket aluminum belly pan for the front and the stock pan in the rear. I am not which vendor the aftermarket unit is from. The problem area is on the cowl for the starter makes contact with the IMI starter when clocked for mounting inboard away from the header.
I was able to resolve the vibration issues by filing the belly pan down where the clearance was the tightest. No more issues.
At first glance, I thought I had enough clearance, I even did a couple test starts on jackstands with video and could see the starter move much at all. And then I realized the bend in the front sway-bar was pushing down the belly pan and little when the wheels were up in the air. Wih the wheels on the ground the belly pan comes a little closer into contact with the starter.
I don’t have headers but mounted the started inboard in order to fit within the heat-shields for the rear belly pan. There is more clearance in the rear so its less of an issue.
Last edited by Michael Benno; 03-25-2019 at 02:13 PM.
11-11-2018, 07:52 PM
