Cutout still exists....., what to try next, I'm going crazy!!! |
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Cutout still exists....., what to try next, I'm going crazy!!! |
porsche735 |
Apr 14 2003, 10:52 AM
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#1
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Member Group: Members Posts: 189 Joined: 10-January 03 From: Los Altos, CA Member No.: 127 |
This is back to the problem in right hand turns and at high rpm. We get a studder until we either turn right to clear it or upshift and hit a lower rpm. We have replaced almost everything. Let me explain what we have done (doesn't mean that a "new" item we have replaced is not bad as well). By the way, the engine has been rebuilt several times over this past 7 years..
Timeline: Problem started about 7 years ago. Had bucking at freeway speeds. Took to Reitmeir's and they replaced the FI trigger points- problem went away. Problem came back again. We "hardwired" the coil to see if it was iginition- was not We rebuilt our FI wire harness and installed new TPS- problem went away for a while Problem came back again. This time also with LEFT hand turns. Replaced the MPS with a rebuilt one- problem went away for a while Problem came back again. Replaced the relay board- no change Installed Pertronix ignitor- no change Moved the fuel pump to front and replaced fuel pump and filter- no change Replaced the FI brain- problem went away for a while Problem came back again. Still left hand turns, but also noticed an RPM sensitivity. Replaced FI trigger points again- problem went away for a while Problem came back again. Replaced the coil and plug wires (but used the same ends)- no change Rented the FI tester from PP and found a suspect wire in our FI harness- problem went away for a while. Problem came back again. Figured our wires in our harness were brittle so we bought a Bowlsby harness- problem went away for a while. Problem came back again. Installed a MSD- don't get me started here but it ruined 4 pistons individually shearing off the ring lans and causing multiple engine rebuilds- removed MSD. Replaced the MPS with a new unit- no change Cleaned up what we think were all the grounds again (firewall by relay board, on the engine for FI, Transmission ground, Battery to chassis ground- that's all, if there are others let me know)- no change Fuel injectors were flowed- engine felt more balanced at idle, but problem not fixed Finally we did this- Connected a long hose to the FI port and attached the pressure gauge so we could see it while running. Used a 2 channel battery powered O-scope and connected to FI#3 and the coil. We ran the car until the problem occurred (just down the street). We saw pressure was steady, coil voltage was steady, FI#3 pulses went to hell- went from nice pulses to noise). We replaced the FI trigger points and re-ran with same setup- problem not seen Problem came back. Latest rebuild of the engine-problem no happens in RIGHT hand turns and with high rpm Decided it must be the distributor as with shaft wobble that would explain the noisy signal on the FI#3 injector (just the only one we wired up not specifically #3, assume them all) , the rpm sensitivity and the turning sensitivity (but no the movement from LEFT to RIGHT this year) Guy at distributor rebuild place said our distibutor was shot with lots of wobble and off about 12 degrees at high rpm. Put in new distributor and it idled better (no hunting) figured we had it licked. First turn at Butonwillow- the problem was back We swapped out with a known good other distributor (thinking maybe the rebuild was bad) and the problem was still there (still in RIGHT hand turns and rpm). Borrowed another MPS from Kevin and Greg- problem was still there. Put in another coil-problem was still there. SO, that brings us to today- I don't get it.... Here is our list of items that could be rpm and/or g related and some notes: FI trigger points- replaced with new distributor, no change- NOT it Distributor- replaced with new distributor, no change- NOT it FI brain- replaced once , but still suspect it there a test for high rpm signal integrity? Rotor cap- replaced, no change Pertronix- replaced with new distributor with point, no change- NOT it Spark plug, coil wires- replaced, no change, but could be possible since old connectors used Relay board- replaced with no change, what really goes bad on these Are there other ground points we are missing? Main wiring harness issue- but doesn't explain the rpm related issue MPS- replaced with working one, no change- NOT it FI harness issues- we have had connector issue with the Bowlsby harness and had to replace one wire going to Trigger points Coil- replaced with another one. One thing I noticed is there is .8v at the negative (#1) terminal and 11.4 volts across #1 and #15. Is this normal, or is there a ground we are missing?- however, hardwiring this in the past had no effect... of course we did not hardwire the ground..., but problem on Oscope showed issue at injectors and coil voltage was constant Fuel pressure- verified with pressure meter during issue, not movement constant 29.5 psi TPS- problem is not full throttle related, but rpm related and it is basically new PLEASE HELP ME!!!! Thanks for all your stabs at this in advance, I will try anything. Chris Kolstad 1973 914 2.0L BP |
Brad Roberts |
Apr 14 2003, 04:42 PM
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#2
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
I can bring 1-2 of them down with me. The problem is: I dont know when I'll be down next.
How I'm thinking on this: You and dad have a bad habit of reusing old parts during the rebuild. I'm betting that Alt has gone through all the different engines.. and its probably the one that came with the car. Before I changed it out.. I would: unplug it completely from the car and drive the car around on the battery. In other words isolate the alternator from the system. This is easy and doesnt require getting under the car. B |
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