89 635 AT no spark

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quadrajet
Posts: 9
Joined: Thu Apr 18, 2019 5:33 am
Location: NW WA

89 635 AT no spark

Post by quadrajet »

On my way home my car just died. Assumed it was the Code relay issue.

Cap and rotor only have 4000 miles on them. I have power to the coil. I have fuel at the fuel rail, fuel pressure when key is in the start position. Motor cranks over when key turned to start.

But found I had no spark. Checked the Crank Position sensor. It was reading 510 ohms. Purchased a new one, it's reading 540 ohms. Installed.
Bypassed code relay by soldering in a jumper at the C2 #4 and C2 #3.
Tested, still no spark.

Tomorrow I'll jumper at the main relay and see what that does for me.

If anyone has some wisdom to share with this situation, I'd appreciate it.
89 635CSI, 91 318is, 91 318ic, 99 525iT(84 325e, 85 325e, 87 325is,91 325i, 88 325, 86 325e, 3-91 318is, 88 535is, 84 633csi, 86 528i Euro, 97 528i, 98 528i, 98 318ti, 99 525i past vehicles)
quadrajet
Posts: 9
Joined: Thu Apr 18, 2019 5:33 am
Location: NW WA

Re: 89 635 AT no spark

Post by quadrajet »

Charged battery overnight, battery at 13.5 volts
Turned key to start with main relay in socket. Still no spark.
Turned key to start with relay bypass wires in socket, still no spark.

I noticed this car doesn't have the speed and reference sensor set up like the earlier cars. It appears more like the set up of the E30 325i cars with the wire connector to a sparkplug wire. These wires were in the car when I bought it.
I'm assuming that act's like a reference sensor for cam position?
Would that keep the ignition from functioning?

Any ideas welcome.
89 635CSI, 91 318is, 91 318ic, 99 525iT(84 325e, 85 325e, 87 325is,91 325i, 88 325, 86 325e, 3-91 318is, 88 535is, 84 633csi, 86 528i Euro, 97 528i, 98 528i, 98 318ti, 99 525i past vehicles)
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Ralph in Socal
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Re: 89 635 AT no spark

Post by Ralph in Socal »

Your 89 is running Motronic 1.3 with a 150 or 179 ecu. That system requires the front crank sensor and the #1 cylinder reference input from the plug wire. Both have connectors at the front of the injector rail. That could very well be the cause of your no-spark issue

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
quadrajet
Posts: 9
Joined: Thu Apr 18, 2019 5:33 am
Location: NW WA

Re: 89 635 AT no spark

Post by quadrajet »

Ralph in Socal wrote: Mon Aug 02, 2021 8:56 pm Your 89 is running Motronic 1.3 with a 150 or 179 ecu. That system requires the front crank sensor and the #1 cylinder reference input from the plug wire. Both have connectors at the front of the injector rail. That could very well be the cause of your no-spark issue

Ralph
I've already replaced the crank position sensor, but could find no test for the reference input.
I've subsequently removed the cap to inspect the rotor. No problems found with those items.
I'll go back and check the connectors at the fuel rail and see if there's any corrosion.
Other than that, I'm wondering if there's anything else I can check before I begin to wonder if the ECU has "retired"?
89 635CSI, 91 318is, 91 318ic, 99 525iT(84 325e, 85 325e, 87 325is,91 325i, 88 325, 86 325e, 3-91 318is, 88 535is, 84 633csi, 86 528i Euro, 97 528i, 98 528i, 98 318ti, 99 525i past vehicles)
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Ralph in Socal
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Re: 89 635 AT no spark

Post by Ralph in Socal »

Pull all electrical connections and inspect for corrosion. Spray with cleaner/lubricant before reconnecting

Remove, and wire brush clean, all ground connections and terminals

I’m not all that familiar with the 1.3 but earlier Motronic requires several +12V inputs along with reference sensor pulses prior to providing spark. Best to study the Electrical Trouble Shooting Guide for your specific model as that should provide test points for the single reference sensor input and +12V locations. You can then probe at the ecu connector and look for those specific inputs. Good luck

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
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Steve M6
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Location: Monterey, CA

Re: 89 635 AT no spark

Post by Steve M6 »

Have you ruled out a bad ignition coil?
'86 635CSi 5-sp
'88 M6 Canadian
'03 530i 5-sp - ordered new, now gone, victim of someone else's spin-out on I880
'02 530i 5-sp - now my daily driver - finally replaced my original 530i
'96 Ford F-150, 5-sp too
quadrajet
Posts: 9
Joined: Thu Apr 18, 2019 5:33 am
Location: NW WA

Re: 89 635 AT no spark

Post by quadrajet »

Steve M6 wrote: Thu Aug 05, 2021 6:43 pm Have you ruled out a bad ignition coil?
In my experience I've never had one fail. But there's always a first time. I'll check that with a known working one, once my back heals. I've been out of action since last Tuesday.
89 635CSI, 91 318is, 91 318ic, 99 525iT(84 325e, 85 325e, 87 325is,91 325i, 88 325, 86 325e, 3-91 318is, 88 535is, 84 633csi, 86 528i Euro, 97 528i, 98 528i, 98 318ti, 99 525i past vehicles)
quadrajet
Posts: 9
Joined: Thu Apr 18, 2019 5:33 am
Location: NW WA

Re: 89 635 AT no spark

Post by quadrajet »

Update
My back has been out for a while and was finally able to work on this issue.

Put in a known good coil, like suggested. Still no start.

Fortunately had ordered in a "new" to me ECU. Started first hit of the key.

Strangely, someone had changed out the ECU before, as they VIN numbers don't match. There was also a strip of masking tape sandwiched in where the pins in the connector are..
89 635CSI, 91 318is, 91 318ic, 99 525iT(84 325e, 85 325e, 87 325is,91 325i, 88 325, 86 325e, 3-91 318is, 88 535is, 84 633csi, 86 528i Euro, 97 528i, 98 528i, 98 318ti, 99 525i past vehicles)
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