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1999 5.7gsi Problems wont plane or go past 2k rpm?
https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=15997		 Page 2 of 3
Author:  LUBA [ Tue Jun 19, 2018 9:38 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Diacom on an laptop is updateable and with different available adapters will work on any boat. Just buy a different cord. Plus way cheaper and a lot quicker than waiting and paying for a dealer......
Author:  ProfitOfDoom [ Tue Jun 19, 2018 3:12 pm ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Well i did the diy test...Came up code 34..which says map sensor signal low voltage..So I guess its safe to assume that I should get a new map sensor?
Author:  LUBA [ Tue Jun 19, 2018 3:22 pm ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Make sure tube and wires for it are good then yes i would replace sensor.
Author:  ProfitOfDoom [ Tue Jun 19, 2018 3:31 pm ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
I checked the tube, I guess I can make sure Im getting power through the wires...then see if I can find a map sensor,,need a direct replacement or think any rated for a 5.7 tbi would do the trick?
Author:  LUBA [ Wed Jun 20, 2018 7:23 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
I would take a pic of the part number and do an online search and buy one. Or possibly go to west marine as they now price match online prices.
Author:  ProfitOfDoom [ Wed Jun 20, 2018 2:29 pm ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Well I put the new map sensor in,and took it out,,It did better,,still a dog on the jam of the throttle,but it built up quicker and got up to plane. Tested it a few times and had the same result each time,,sluggish at first then gradually picking up speed then once I get up to plane rpms jump higher into the normal range and will continue just fine.

I tried to clear the code and im pretty sure it worked but when I came back from my trial run,I plugged up the diy code reader again and it was showing that same code even after the replacement of the map sensor "code 34" Im gonna try to clear it one more time "maybe I did it wrong" do another test ride and see what happens.

A guy down at the marina said maybe my DP props are not aligned up right,I thought I read before it didnt matter which way they go on,Could this be a issue?
Author:  LUBA [ Thu Jun 21, 2018 5:57 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
ProfitOfDoom wrote:
A guy down at the marina said maybe my DP props are not aligned up right,I thought I read before it didnt matter which way they go on,Could this be a issue?


Huh? They are counter rotating props. As long as they are all the same pitch (i.e. F6) and they are installed properly front to rear-which I don't think you can screw up. No idea what he is talking about. Unless he means balanced and reconditioned.
Author:  Jsyphil [ Fri Jun 22, 2018 3:09 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
ProfitOfDoom wrote:
Well I put the new map sensor in,and took it out,,It did better,,still a dog on the jam of the throttle,but it built up quicker and got up to plane. Tested it a few times and had the same result each time,,sluggish at first then gradually picking up speed then once I get up to plane rpms jump higher into the normal range and will continue just fine.

I tried to clear the code and im pretty sure it worked but when I came back from my trial run,I plugged up the diy code reader again and it was showing that same code even after the replacement of the map sensor "code 34" Im gonna try to clear it one more time "maybe I did it wrong" do another test ride and see what happens.

A guy down at the marina said maybe my DP props are not aligned up right,I thought I read before it didnt matter which way they go on,Could this be a issue?


Glad to hear you're making progress, and it's currently DIY so not costing you a fortune in mechanics fees.

Although these issues are sometimes very frustrating and not immediately easy to fix, i'm sure we'll win in the end!

As mentioned the prop comment is irrelevant and i'd forget about that.

I'd check you cleared the code, and try again, although as it didn't run perfectly i'd sense there is something else amiss.
The fact at High RPM it ran well and fine is a good thing, we're getting there.

The MAP Sensor, Air Idle Control Valve and Throttle Position Sensor are very closely linked on these engines with Early Fuel injection and work together; it is very possible that there is an issue with something else which is causing the ECU to assume the reading from the MAP Sensor is incorrect.

Out of interest, in Neutral, does it freely rev up and down the range? Are the issues just when in gear and moving under load??

The first thing that springs to mind is the Throttle Position Sensor, this reads how open the throttle is and together with the Manifold Vacuum reading tells the ECU Parameters related to load, performance, and fuel metering.

It's possible the TPS isn't functioning correctly and the ECU is assuming the fault is with the MAP Sensor; i'd test the Throttle Position Sensor, which you can do with a multimeter. It should read under 1 Volt at idle, to about 5 volts or so at WOT. You can test this with the engine not running, by the way, it is much safer. If the Throttle Position Sensor has worn and the voltage reading at idle/low speed is incorrect then this may be the cause of your issues.

The second thing to check is that the Air Idle Control Valve is moving and isn't stuck closed. With the air filter off the engine, looking into the throttle plate, have an assistant turn the key - not to start the engine but just from 0 to 1, the position before turning the engine over. The fuel pumps should come on but also - the Throttle Position Sensor should buzz and the pintle should move a tiny bit back and forward.

I must say in situations like this, I'm very hesitant to just buy parts without testing things first, as it can be an expensive, frustrating and fruitless way of fixing problems - so although this problem is annoying - please please please persist with checking things before buying new bits - The MAP Sensor may well have been dead but you will end up spending unnecessary money by just changing things without electrically testing them first!

If it helps i have a MEFI Diagnostics manual on pdf from when i had these issues with my boat. It's almost 300 pages long and very comprehensive, but may help as it shows all trouble codes and then has schematics of how to test and diagnose based on the code that flashed up.
If you think it will help then PM me your email and i'll email it to you - like i say it is very comprehensive though!!

But... for now, i'd check the code was clear and go for another run - if it's still not running right and the code reappears - and the MAP Sensor is new, The hose and wiring to it is good and functioning, I'd check the Throttle Position Sensor is working correctly, and the AICV moves.


Cheers
Phil
Author:  ProfitOfDoom [ Sat Jun 23, 2018 5:31 pm ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
I took it out for a run and still ran the same. It would get up on plane but only after a few mins building up speed gradually..then on plane it will finally pass the 2k rpm and go up to around 3k -3,500rpm and maintain like that fine.

On the way back I had the wife drive and everything seemed fine..look like it was getting plenty of gas getting dumped down there and throttle plate opened fine.

So on the way back I just floored it and it did the same thing..just doesnt seem to want to take the gas and it even backfired on me this time.

Got back and checked for the code...The code was still gone. I checked the voltage on the Tps and that worked fine. Also looked at the pintle..it was hard to see but I had a micro camera thing..and when the key was on..I didnt see any movement..but when the key was turned off..it did move back and forth like you said.

So im unsure what to look at now..
Author:  babbot1 [ Sun Jun 24, 2018 6:42 pm ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Sounds similar to my issue last year. I have a different engine but maybe similar. My merc 8.1s have 2 fuel pumps, a main pump and a booster pump. The booster pump was not working and i couldn't get on plane. If I tried too hard it would backfire. Replaced the booster pump and everything worked as normal. I am not sure how you can test that pump but I knew it was the booster. It did the same thing on our sea trial and that's what the marina replaced on the other engine.
Author:  Jsyphil [ Mon Jun 25, 2018 9:12 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Sorry to hear it's not good yet - this seems like it's a tricky one.

Have you checked fuel pressures, on the High & Low side? There are schraeder valves at two points to do this with a fuel pressure gauge.
The other thing to check is the injectors, i'm sure you'd see if one wasn't working, but with a timing light hooked up to a spark plug you can see if the spray patterns are equal, or if they are significantly different,

When was the last time the plugs/distributor cap was checked/changed?
Author:  ProfitOfDoom [ Tue Jun 26, 2018 1:53 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Yea Ive checked the fuel pressure, the high pressure was 30psi and the low was 5psi. I havent checked with a timing light, but they look the same by just looks.

Last year I changed the cap and rotor and plugs, this season I replaced the wires.
Author:  Rick2752 [ Tue Jun 26, 2018 4:03 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
My guess is the fuel pump screen is clogged on the high pressure side. If you take the pump off and look at the bottom it has a very fine screen. The new pumps are no where near as fine. You have pressure but no the volume you need


Rick
Author:  Jsyphil [ Tue Jun 26, 2018 4:53 am ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Good thinking Rick, a good one to check...
Author:  ProfitOfDoom [ Wed Jun 27, 2018 8:25 pm ]
Post subject:  Re: 1999 5.7gsi Problems wont plane or go past 2k rpm?
Thanks for the tip..Are these screen replaceable or do I just have to try to blast it with some carb cleaner or something?
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