Bucking under acceleration
#46
Rennlist Member
Thread Starter
I'm going to try your way. I'm going to take the metal cover off to securely attach it. I did notice that when I take off the spark plugs, the cap pulls away from the metal cover. Which, I now assume, is part of the issue.
Thanks again
Thanks again
#48
Rennlist Member
Interesting. What brand is the one with the short hooks? Do you think you seated them as best possible, and they came loose on their own because the hook parts don't extent into the notch very far? If so, I'm sure Rennbay would want to know. If it helps, here are some shots showing a healthy cover with well-defined notches for the hooks, along with a shot of Bosch hooks (like yours) and how the look seated.
#49
Rennlist Member
Thread Starter
The one that I got from Rennbay does not have any identifying marks on it but looks like the Bremi unit that's found on the Pelican Parts website. I ordered the Beru one from Pelican, which should be delivered tomorrow. Hopefully it seats well. I do think that the shorter hooks are the reason why they came loose, though. You can see in the picture how little clearance there is and with vibration what would happen in there. I'm just surprised to see that there are differences in the hook length by these manufacturers.
#50
Rennlist Member
Thread Starter
From left to right: Bosch-longest hook length, Beru-medium hook length, Bremi-short hook length. Apparently, hook length matters for my '89 Turbo.
#52
Rennlist Member
Good info, thanks. I always buy Bosch just because of its reputation for quality -- seems like it kind of earned it here. Fingers crossed! With our current local weather, all you need now is a rudder and an outboard motor and you can give it a test run.
#53
Rennlist Member
Thread Starter
Notches are good. But weather now doesn't make me feel like I'm in a rush to put it back on to test it. At some point, we should have a South Bay 944 get together though. If this doesn't fix it, I may be heading your way anyway!
#54
Rennlist Member
Yeah, we are long overdue for a get-together. Maybe in the spring when the weather picks up...
#55
Rennlist Member
Thread Starter
Still having problems so I installed a WBO2 sensor( the PLX unit) and my car is running lean at 3/4 and at WOT. I get 14.7 at idle but it's hitting 15 and as much as 16 at WOT. I'll be checking and changing the FQS setting to the +6% setting to start. What else should I be checking?
#56
Banned
Still having problems so I installed a WBO2 sensor( the PLX unit) and my car is running lean at 3/4 and at WOT. I get 14.7 at idle but it's hitting 15 and as much as 16 at WOT. I'll be checking and changing the FQS setting to the +6% setting to start. What else should I be checking?
If these don't solve it than I would replace the injectors.
#58
Rennlist Member
Since the issue "seemed" to go away when you improved the ignition last time, I wouldn't necessarily give up on that just because you are seeing lean AFR readings. A misfire caused by weak spark will cause the gas not to burn, which will let a lot of extra oxygen sneak out the exhaust, which will trick the wideband into saying the mixture is lean. You could have a perfect AFR, but if the gas isn't burning right, the wideband will say it's lean. I'd still want to check the fuel pressure as Jimbo suggests (and add the regulator to his list), but keep an open mind about where to look, including the ignition still. If you can hook up some way to monitor fuel pressure at the rail under load, you'd know if the fuel system were the culprit.
Is it still only having problems when you floor it above 3000 rpms? Does it pull hard to redline if you floor it from say 2500? That's what I understood from your first post. If so, I wonder if the cylinder or boost pressure is shutting down an injector or its driver, or the FPR or something when it goes from mild to wild all the sudden, but is able to keep working if the pressure increases more gradually? If you slowly roll on the gas above 3k until you get to WOT, does it still have the issue? What's the AFR when it does pull hard?
Have you ever checked your DME and KLR for cracked solder joints, or tried spares? One thing I'd want to test is to see if the "full load" signal is being triggered when you floor it. That signal sends the DME into the WOT maps, so if it's not working right you will be on the partial throttle maps even though your foot is to the floor. You can lose that signal from a bad TPS or bad KLR/DME. Bench testing parts is a great way to confirm they are BAD, but only a so-so way to confirm they are good. If the problem is intermittent, or only shows up under certain conditions, bench testing may give you a false positive -- swapping in known-good parts may seem ham-fisted, but it's a pretty good way to isolate intermittent issues....
Did you cap off your evap system? If so, try driving with the gas cap off.
Bad/dirty ground straps can cause bizarre faults too -- have you cleaned those up and checked them, especially at the bell housing?
Is it still only having problems when you floor it above 3000 rpms? Does it pull hard to redline if you floor it from say 2500? That's what I understood from your first post. If so, I wonder if the cylinder or boost pressure is shutting down an injector or its driver, or the FPR or something when it goes from mild to wild all the sudden, but is able to keep working if the pressure increases more gradually? If you slowly roll on the gas above 3k until you get to WOT, does it still have the issue? What's the AFR when it does pull hard?
Have you ever checked your DME and KLR for cracked solder joints, or tried spares? One thing I'd want to test is to see if the "full load" signal is being triggered when you floor it. That signal sends the DME into the WOT maps, so if it's not working right you will be on the partial throttle maps even though your foot is to the floor. You can lose that signal from a bad TPS or bad KLR/DME. Bench testing parts is a great way to confirm they are BAD, but only a so-so way to confirm they are good. If the problem is intermittent, or only shows up under certain conditions, bench testing may give you a false positive -- swapping in known-good parts may seem ham-fisted, but it's a pretty good way to isolate intermittent issues....
Did you cap off your evap system? If so, try driving with the gas cap off.
Bad/dirty ground straps can cause bizarre faults too -- have you cleaned those up and checked them, especially at the bell housing?
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Droops83 (01-24-2020)
#59
Rennlist Member
Thread Starter
I changed the fqs setting and it seemed like a so far so good solution (I was only able to do a quick 3rd gear pull). I'll take it to work tomorrow and check it out more thoroughly.
I have a new DME for F9Tech as of 9/17 and I thoroughly went through all of the grounds and replaced both the positive and negative cables a couple of years ago chasing a "no start" issue. It was a corroded positive cable.
Thanks again for the help!
I have a new DME for F9Tech as of 9/17 and I thoroughly went through all of the grounds and replaced both the positive and negative cables a couple of years ago chasing a "no start" issue. It was a corroded positive cable.
Thanks again for the help!
#60
Rennlist Member
Keep in mind, unless the base tune is just off, then adding extra fuel via the FQS is just masking whatever the issue is. It doesn't sound like your issue is just a bad base tune, since the problem is intermittent...
Also, cracked joints in the KLR are still possible.
Also, cracked joints in the KLR are still possible.