Possable fuel delivery issue with the E 420

[Ascension]

Here is what's going on car runs perfectly most of the time. However on a brisk acceleration it has suddenly fell on it's face like it hit the limiter then came back a couple times lately. Well today I got her into a good pull in 2nd gear coming up an on ramp and at WOT about 4000 it just suddenly fell on it's face shut down for a second came back then did it again right at 5000. As soon as I backed off the throttle it was fine. Had only stumbled for a second only twice before and that was when it came up on the cams on a brisk acceleration and just for a second. Feels like a fuel delivery issue to me the way it acted but?? Any suggestions on where to start on diagnosing it? Anything else that would cause this? For me it coming back when I back off the throttle and acting normal is telling me this is likely a fuel issue. How many fuel filters on these just the one or?
Do have a bad ETA ( non ASR car) so it has a surge in idle plus cruse is in op. I need to get Roden to build me a ETA and get it on..

 

[gsxr]

When it faceplants, is it smooth like restricted fuel? If so, how old are the fuel pumps? Fuel filters don't cause intermittent problems, but the pumps do. Unless your car is a late build 1995, it will have 2 fuel pumps. If it's late 1995, it will have a totally different fuel pump package with a single pump and different filter design.

The proper way to diagnose is connect a fuel pressure gauge that is visible while driving and see if pressure drops drastically when the power loss occurs. Not many people have the gauge/hose to do this. It's helped me diagnose at least 3 different cars with a similar problem to what you descirbe.

 

[nocfn]

just a comment, I hit the rev limiter in 2g and it was quite an oh SH$& moment. Once I realised it, we were good to go manually shifting thru the gears prior to stated points.

 

[Ascension]

When it faceplants, is it smooth like restricted fuel? If so, how old are the fuel pumps? Fuel filters don't cause intermittent problems, but the pumps do. Unless your car is a late build 1995, it will have 2 fuel pumps. If it's late 1995, it will have a totally different fuel pump package with a single pump and different filter design.

The proper way to diagnose is connect a fuel pressure gauge that is visible while driving and see if pressure drops drastically when the power loss occurs. Not many people have the gauge/hose to do this. It's helped me diagnose at least 3 different cars with a similar problem to what you describe.

It just shuts down like it hits the limiter then comes right back. Has done it a total of 3 times. First was just in a brisk acceleration and it suddenly stuttered. The second and 3rd were yesterday the first during the pull the second soon after in a brisk acceleration very quick but felt it. During the pull it fell flat on it's face twice like you flipped the switch off then came right back. Had been putting around town and had it on an incline where I could pull into it and pull it to redline to clean it out a little so--. Never done this before it got my attention and I don't know this system well enough to really know where to start on a diagnosis.
Have no record of pumps ever being changed. Would the VIN tell you if it has one or 2 pumps or maybe filter placement or ? It is a 95.

 

[Ascension]

just a comment, I hit the rev limiter in 2g and it was quite an oh SH$& moment. Once I realised it, we were good to go manually shifting thru the gears prior to stated points.

Have also hit the limiter felt exactly the same.

 

[gsxr]

VIN will show if it's a single or dual pumper.

From your description I'm having a hard time telling if it's a smooth power loss or a hard shutoff. The latter is more likely to be an electrical / control issue of some sort, need to check codes on all modules, yadda yadda.

 

[Ascension]

VIN will show if it's a single or dual pumper.

From your description I'm having a hard time telling if it's a smooth power loss or a hard shutoff. The latter is more likely to be an electrical / control issue of some sort, need to check codes on all modules, yadda yadda.

Hard very abrupt shut off like you flip the switch. It pulls strong and clean then suddenly falls on it's face very abruptly. There is no smooth shutdown and it feels almost exactly like hitting the rev limiter does.
This is why I'm thinking a fuel issue.

 

[gsxr]

What codes are present, on which modules?

 

[nic520]

A hard shutdown does not sound like a fuelissue, I would agree with Dave. It sounds more like the overload switch of the transmission.

 

[Ascension]

What codes are present, on which modules?

Got to get a break in the weather to pull them. Cold and rain here and only have an open carport. Will get codes as soon as the weather breaks.

 

[Ascension]

Now looks like I had a problem with my LH. Had a 91 dated LH with full enrichment in the car. Was also having issues with it not going into cold start and a couple other things that made me suspicious so I dropped the original LH back in the car. Noticed an instant improvement in drivability at part throttle. The cold start issue is now gone and I had thought I had a exhaust issue as when cold heard a weird rattling as the car came on the power band. That instantly vanished with the original LH and normal drivabilty is noticeably different. Car is not as peaky power band is more consistant and smoother. Should have no effect in part throttle performance but did and noticeably so. The car has pulled to redline with no issues but at WOT you can sure feel the power loss without the full enrichment. Was stunned at how much difference the swap made in overall drivability on this car. Need to get into that 91 LH for a post mortum.

 

[nic520]

Thank you for the update! But the WOT LH did not have those issues from the beginning/mounting, right?
Would be interesting to know which detail of the LH failed.

 

[Ascension]

No it happened slowly over time. the weird is that rattle when it came on the power band when it was below op temp. Now wonder if it wasn't leaning out and going into preignition? Need to pull a plug and read it.

Had something fly out from under a truck on the highway and bounce under the car a couple months ago that took out my tow hook cover on the front bumper bounced under her then cut the left rear down and gouged the rear bumper cover on the way out. Thought the weird noise may have been a slight exhaust leak showing when cold from that I had missed when I did an inspection but--.. Started a couple weeks ago and is now gone with the other LH so??? Throttle response in normal driving is notably different as before the car was very peaky sluggish then came on with a rush almost like a turbo car coming on boost.

Now is MUCH smoother and more even so something was definitely going south with that LH as should have been the same until WOT. Non-ASR car and don't fully understand what controls what between the LH and EGAS T/LLR. Haven't really gotten the car out much since the swap so lets hope it all holds.

 

[Ascension]

Update after driving it again today for a while. Throttle response is much better and even the trans shift points have changed from the difference in the throttle position I would guess. Car has a bad ETA so idles high and has a surge when at idle in neutral. Surge is now much better idle is much lower right at a grand in neutral where it was bouncing up to around 1300. Something has definitely went south in that LH that's for sure.
Got to get Roden to build me a ETA!

 

[Kyiv]

Something has definitely went south in that LH that's for sure.

If you open it, you'll likely find leaked capacitor/s. There are 6 of them. Replacing them fixes the module.

LH Module cross Test and Repair - Capacitor replacement | Electrical, CAN and Wiring

ADMIN UPDATE: Additional information on replacement caps at this post. Also, forum member @Alphasud offers a capacitor replacement service, click here for details. First, I have to say this forum is very good that I didn't seen before. Everyone share know-how and help each other. Some...

www.500eboard.co

 

[Ascension]

Plan on opening the LH but have to find the right tool.The 2mm Allen won't do it and 2.5 is to big must be something other than an Allen that holds the covers.

 

[gerryvz]

I think it is a Torx bolt.

 

[gsxr]

Torx T10 and/or T15, depending on the production date of the module.