GT-40 PCM Running RIch, sometimes
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=47686
Printed Date: April-26-2024 at 8:38pm
Topic: GT-40 PCM Running RIch, sometimes
Posted By: workky
Subject: GT-40 PCM Running RIch, sometimes
Date Posted: July-05-2019 at 12:57pm
|
Hey guys I have the first year GT-40 in my boat with no FCC. We have had quite a few issues in the past with the engine management. I will someday replace the crappy ECU with something i can control from my laptop. Now, the issue i will describe is unusual Boat runs fine, cranks up fine, drives fine, does everything fine because it's mine. However, at Idle after a while it starts running rich. Rich enough to see black smoke coming out the exhaust. When you raise the RPM or get under way to about 2k RPM is goes away and does not come back. It will come back after an extended IDLE It only does this at IDLE for extended periods of time, it may or may not do it, there is no consistency. Whats wrong??? |
Replies:
Posted By: tryathlete
Date Posted: July-06-2019 at 12:50pm
Since your issue seems to be related to idle why not see if your IAC is dirty? I’d pull the flame arrestor and see if cleaning up the IAC will fix it. Look for a few other easy places like your cap and rotor. Finally; another easy one; how is your fuel? Do you have last years gas still in there with ethanol degrading or water trying to get through your injectors? |
workky wrote:Posted By: workky
Date Posted: July-06-2019 at 1:57pm
|
It is last years gas!!!!! However, it did the same thing last year. I'll clean the IAS or whatever it's called. Thanks for the suggestion, I'll do it today and report back |
Posted By: tryathlete
Date Posted: July-06-2019 at 2:52pm
| I ran only ethanol free premium always because I don’t like what happens to ethanol over the winter even with stabil. Why risk it? Ethanol is junk. |
Posted By: 8122pbrainard
Date Posted: July-06-2019 at 3:32pm
I've run ethanol in everything since it's inception and haven't had one problem. It's great stuff. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: tryathlete
Date Posted: July-06-2019 at 5:39pm
Hope you’re not serious. Maybe just run straight ethanol then Pete. Great stuff! |
Posted By: 8122pbrainard
Date Posted: July-06-2019 at 5:50pm
Peter, I'm very serious. Again, I've used it since it's inception and NO problems. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: KENO
Date Posted: July-06-2019 at 7:57pm
You know I hate to agree with you Pete (Brainard), it really pains me at times  But I'm feelin' real pained right now since I completely agree with your ethanol experiences all year round. And I'm being serious. I'm talking about today's gas with 10% ethanol No issues |
Posted By: 8122pbrainard
Date Posted: July-06-2019 at 8:58pm
|
When the "mechanic/tech" can't figure out the problem, it's typical he blames it on bad gas!! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: gt40KS
Date Posted: July-06-2019 at 11:07pm
|
Getting back to the issue and question at hand ... bad gas aside (or just crappy gas depending on who's speaking) two things pop into my head, that haven't already been mentioned anyway. Overpressure in the fuel rail. Or you may have a few injectors getting old and starting to drip. I've been told when this starts to happen it is more prevalent at idle and very low rpm which can load up fairly quickly and cause just the issue you're having. Just a thought. ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: Jonny Quest
Date Posted: July-07-2019 at 3:09am
|
I think GT40KS is correct. I'd look at the fuel injectors and associated systems. When the throttle-body fuel injection was failing on my 1994 PCM, I first noticed black smoke at idle. There was so much black smoke that I had to wipe the black soot off the stern after skiing. A dirty, clogged or failing injector that isn't properly atomizing the fuel certainly can cause an over-rich air/fuel ratio at idle. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: MrMcD
Date Posted: July-07-2019 at 5:46am
|
My son runs a Corvette with Twin Turbo's, on premium gasoline he makes 738 HP at the rear tire. On the E85 he can run higher boost and more timing with no detonation. The Horsepower jumps to approx 900 at the rear tire. No joke. You can make great power on E85 but the alcohol can be corrosive and hard on the fuel system. He can flash his computer in about 5 minutes to run on either gas. He has developed 2 separate tunes. I think with E85 he is running 21 pounds of boost and recording zero detonation. Not so sure it would work that well with carbs. ------------- |
Posted By: tryathlete
Date Posted: July-07-2019 at 6:12am
Hopefully he doesn’t fill up his gas tank in September and plan to use it in June the following year like many of us do up North. Phase separation of alcohol from gasoline and water absorption don’t work well with SOME of our marine engines. My local small engine repair guy won’t work on chainsaws and line trimmers without changing the fuel to ethanol free premix gasoline. |
Posted By: workky
Date Posted: July-07-2019 at 1:45pm
|
https://m.youtube.com/watch?v=p7N_cv-Da5o" rel="nofollow - video The video above was taken yesterday. I decided to check vacuum. I know bad gas can cause issues, and granted this stuff is old. However, it was doing the same thing all last year with new gas Fuel pressure is fine, checked that as well. Im.more concerned about the vacuum issue. And, no obvious vacuum leaks. Which points me to a leaking valve, rings, etc. I suspect I have a valve to tight. However, these rocker arms are non adjustable. I'm doing compression test today to try and find out of my thoughts are correct. This vacuum.leak takes priority right now. New stuff within the last year New fuel injectors Fuel Pressure regulator Low pressure pump IAS idle air thingy Water temp sensor Plugs, wires, cap, rotor MAP Relays both ECU and fuel Within the past 2 years GT40X Aluminum heads PIP Sensor New shift and throttle cables |
Posted By: KENO
Date Posted: July-07-2019 at 7:03pm
|
What was the outcome of this thread in the link below, where you had intermittent smoke and one fouled plug. ? Sounds like things could be related http://correctcraftfan.com/forum/forum_posts.asp?TID=46760&KW=&title=intermittent-smoke-gt40" rel="nofollow - link |
Posted By: workky
Date Posted: July-07-2019 at 9:23pm
| Nothing, still goes it and cant figure it out. Low vacuum is main concern now. If it wasn't for you I would have forgot I posted that, i cant remember 2 hours ago |
Posted By: KENO
Date Posted: July-07-2019 at 10:53pm
|
So.........putting the 2 threads together, you suspect issues with one cylinder and you have one with a loaded up plug. Sounds like a good place to start looking Is that pitch black plug oil covered or fluffy black and gas fouled? That would probably help you figure out if you should be looking at injector problems or mechanical issues with that cylinder Maybe a compression test will be informative |
Posted By: workky
Date Posted: July-08-2019 at 1:26am
| Compression test is tomorrrow |
Posted By: KENO
Date Posted: July-08-2019 at 10:07am
| There's a guy with the same name on PN with the same problem, but he posted more info over there like a trouble code.................why is that? |
Posted By: tryathlete
Date Posted: July-08-2019 at 10:30am
PN is a waste of time for technical help on GT40 and other engine troubleshooting issues. Good place for stereo advice and ballast system engineering! |
Posted By: KENO
Date Posted: July-08-2019 at 11:24am
I don't quite think I'd say that Just as one example, where did the GT40 ECU fix come from ? I figure Workky can.t figure out how to post a picture here but I'm not sure. |
Posted By: tryathlete
Date Posted: July-08-2019 at 8:23pm
| You’re right. PN is capable of being good for troubleshooting at times. There are a few guys on this site that never fail to get folks across the goal line though 😃 |
Posted By: slmskrs
Date Posted: July-09-2019 at 1:36am
Not to sidetrack your thread, but I'm looking at replacing my injectors. Where'd you get yours? I'm not going to pay PCM's price.... Thanks, Gordon ------------- Gordon '97 Ski Nautique, GT40 |
Posted By: Gary S
Date Posted: July-09-2019 at 2:14am
|
Let's see what he used but Ford Motorsport M-9593-LU24A are a good choice.Many places have them- around 215 a set,just google them. Will need EV-1 to EV-6 adapters for the wiring harness also. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: workky
Date Posted: July-09-2019 at 3:59am
|
I dont remember where we got them, I think summit racing. I believe they were around 200 hundreish a set, for some reason I remember something like what Gary said about the connectors, and for some reason I think the injectors are pink. I'll look at them tomorrow |
Posted By: workky
Date Posted: July-09-2019 at 4:07am
KENO, you are quite the investigator. You are right, I have no idea how to post a picture here. As I've said many times, I can't remember 2 hours ago. So if I post so.ething on PN I cant even tell you what I posted, hell I do t even remember what I posted here, I forget and dont do searches like I should |
Posted By: MrMcD
Date Posted: July-09-2019 at 6:06pm
|
Your idle vacuum at 15 is not terrible, you may have weak compression or maybe your timing is a little retarded. The fact it is bouncing between 15 and 15.5 is not an issue. Bouncing vacuum would refer to bouncing between 12 and 17, you don't have that. How did your compression test turn out. ------------- |
Posted By: workky
Date Posted: July-11-2019 at 2:02am
|
150 psi on 6 cylinders 155 psi on one And 147 on one |
Posted By: KENO
Date Posted: July-11-2019 at 9:11am
No problem with those readings as far as consistency from cylinder to cylinder. Which reading was from the cylinder with the black plug Have you tried the vacuum gauge on another engine to see if maybe the little fluctuation is due to bad dampening or if it's steady on the other engine? Or hold your RPM's steady at say a couple thousand and see if the gauge is fluctuating slightly or does it smooth out. Just me thinking but I think you have a bit of a misfire on the cylinder whose plug is black if the fluctuation is real |
Posted By: workky
Date Posted: July-12-2019 at 1:53am
|
I hooked it up to my Honda accord , it was steady at 22. You are right about the misfire. Number 6 plug wire is bad according to the om meter. Replaced the wire and plug in number 6. However, it still smokes, but not as bad. I looked at the injector and its pink, the others are blue or black I cant recall. It is clear that we have changed it at some point, and it may have been the wrong one or is leaking. But I cant freaking remember when we did that. As is said many times I cant remember crap anymore, and I'm in my 40's. I ordered a set of injectors 15 minutes ago. I know they are all not bad, but they sure are old and probably need replacing. A leaking injector is the only thing else I can think of that would be causing this. |
Posted By: workky
Date Posted: July-12-2019 at 2:01am
|
I will add yesterday it would only pull 4400 rpm and it skipped like crap. today it pulled 5000 and ran like a champ. Of course I know the engine should not run this fast, it's just the prop. It runs fantastic under power and it idles great, just that stupid smoke |
Posted By: tryathlete
Date Posted: July-12-2019 at 5:26am
| I can’t wait to hear how it runs after you swap in those new injectors. |
Posted By: workky
Date Posted: July-15-2019 at 1:39am
|
I hope it runs fine. My concern is I just dont see how one cylinder could be causing that much smoke. I'm testing the injectors tomorrow for leaks or dripping. I'm also testing the water temp unit that goes to the computer. Number 6 cylinder had a bad wire and fouled plug. This engine has always laughed at me when I've tried to figure out issues with it. I don't understand the GT40 engine, wish I had a LS engine in it. Nothing is ever easy with this boat |
Posted By: workky
Date Posted: July-21-2019 at 5:28pm
| Well, I replaced all the injectors. I did not test to see if the old ones leaked. My girls were dying to ride the tube. The boat runs fantastic. However , it still has that smoke at idle, it's not as bad as it was, but it's still there and ita driving me crazy |
Posted By: slmskrs
Date Posted: July-24-2019 at 4:02am
Where's you get the injectors? :) Also, probably a lame question, but how about your oil level? I assume it is not too high. ------------- Gordon '97 Ski Nautique, GT40 |
Posted By: workky
Date Posted: August-01-2019 at 12:41am
|
Oil is right in the money, I got the injectors from Amazon . The injectors are ford motorsport something or another, they are purple. They do require these littke adapters that you can order seperately or the come with them on one website. |
Posted By: workky
Date Posted: August-04-2019 at 2:33am
|
https://youtu.be/CTjs7PrjRr4" rel="nofollow - video This is a video i made of the smoke at idle. It wont do it unless its at idle. |
Posted By: MrMcD
Date Posted: August-04-2019 at 4:24am
|
I am suspecting coolant in your cylinders with all that smoke/steam out the exhaust. Does the exhaust smell rich with your new injectors installed? If it is strong rich it cerainly is not caused by a coolant leak. Run it a while and take a look at your spark plugs they may help point what direction to go on this next. I have not checked vacuum on my GT40 but I can one of these days. I am not certain what number would be normal for a GT40. If you are burning enough oil to make all that smoke I would be thinking about the intake manifold gaskets sucking oil into the engine. ------------- |
Posted By: KENO
Date Posted: August-04-2019 at 7:43am
Right under his video in pretty big letters he says "the smoke smells like gas not oil" |
Posted By: 8122pbrainard
Date Posted: August-04-2019 at 9:32am
|
To me, it looks like steam from the hot moist exhaust reaching the dew point. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: gt40KS
Date Posted: August-04-2019 at 12:52pm
|
Ok Brent, I was just reviewing your post update from a few weeks ago where you listed all the repairs and modifications you've done in the past and I think I have a possible diagnosis, and maybe a solution. [quote from post] Within the past 2 years GT40X Aluminum heads PIP Sensor New shift and throttle cables I'm thinking it may be those new aluminum heads that's causing your issue. The GT40 'X' heads go up from the original 1.85" intake valves to a larger 1.94" valve while the exhaust valve remains the same. The stock PCM ECM can't compensate for the extra fuel, especially at idle, so it's probably loading up while idling. Similar to my situation where my engine rebuild created a larger displacement which then cause a slight lean condition at idle, yours is flowing a bit too much fuel due to the bigger valves. If I'm correct, I'm thinking the same solution would work for you: get an adjustable fuel pressure regulator. But in your case you'd be dialing the pressure down a bit. Well, that's my theory anyway - certainly wouldn't hurt to give it a try at this point. ------------- JCCI 1995 Ski Nautique GT40 |
Posted By: workky
Date Posted: August-04-2019 at 2:20pm
|
When we put the heads on, it ran like a seeaming eagle, no issues what so ever. This smoke signal thing, i believe started last year. I cant remember. The smoke may look blue white whatever, you stick your head back there and get a wiff, its gas. All plugs look great, exept for number 6. I can pull it out right now and it will need replacing, it will be gas foulded. You can hear something change in the sound of the engine when it does it. It wont do it above 1k or 1200 i cant remember. |
Posted By: workky
Date Posted: August-04-2019 at 2:25pm
|
Ive gone on the war path because im pissed. I broke a plug wire connector yesterday. So i ordered a complete new ignition system from distributor to plugs, coil, cap, rotor, module, ect. The distrubuter looks like crap on the inside. Rusted, and what not. Im upset that the pcm red wires we replaced not long ago had a failed number 6 wire, which i replaced. I would ohm the rest, but im just replacing them all. |
Posted By: KENO
Date Posted: August-04-2019 at 2:28pm
This was mentioned before but I'll mention it again rather gently . .................don't you think that's telling you something?You also mentioned a different color code on that injector |
Posted By: workky
Date Posted: August-04-2019 at 2:36pm
| I know, the injector was pink. However, it has all brand new injectors now |
Posted By: KENO
Date Posted: August-04-2019 at 3:01pm
|
Your timeline is hard to follow but then as you say you have a hard time remembering what you did. I think I'd do all the ignition system stuff you have planned and see if that cures things before doing any more fuel system stuff just so you're only messing with one system at a time |
Posted By: workky
Date Posted: August-04-2019 at 3:06pm
|
I know, my brain is fried. The fuel system is all new. I swapped computers yesterday (i have an extra one) it still did the same thing Q Ill get it, i know im not probably diagnosing things the way they should be done, but this stuff is old and if its not bad, it may go bad soon |
Posted By: KENO
Date Posted: August-04-2019 at 3:19pm
|
I know you'll get it too It seems like there have been plenty of GT40 oddball issues fixed with a whole new distributor |
Posted By: workky
Date Posted: August-24-2019 at 11:12am
|
Hey guys, how do you add pics? Going to need some opinions The issue is its not running rich anymore. It still smokes but its blue and sometimes grayish. And only smokes below 1200 rpm when vacuum is high. Boat runs phenomenal. Pulled exhaust last night. Have milky colored oil in exhaust port. Spark plug shows no water , only oil foulded. Compression is 150psi Has oil sitting on top of piston, piston looks good from limited view with camera. I pulled it my buddys house. He is service manager for Honda, He noticed the head bolts near 6 was leaking oil. Pulled head bolts and they looked like crap. Replaced them and resealed them with Honda bond on the threads. Is it possible for the bolts to leak internally ? I have pics i nees to upload. We killed 20 beers looking at this thing. |
Posted By: KENO
Date Posted: August-24-2019 at 8:21pm
| How about leaky valve stem seals or a leaky intake manifold to cylinder head gasket letting oil get into what I'd guess is the #6 cylinder still having issues |
Posted By: workky
Date Posted: August-24-2019 at 11:05pm
|
Number 6 is the issue. We ran the camera down the lower intake port aftwr we removed the upper. Everything looks nice and clean, no oil. One thing i left out. The heads were replaced because someone ran the boat hot and messed the old heads up. This was done about 3 years ago. My brothers partner did it, but getting him to describe what occurred was like pulling teeth from a great white. He is not at all mechanically inclined, hes one of those georgia tech grads. Anywho number 6 i believe was the cylinder that had the worst compression at th at time. It was 80psi. I pulled the heads, checked the block visually. Heads were trashed. Replaced with GT40X. That was 3 or 4 years ago. But it seems that maybe we have a issue with that cylinder, piston, or block |
Posted By: tryathlete
Date Posted: August-25-2019 at 5:37pm
| History is everything. Knowing it makes figuring things out a lot simpler. Changing heads for an 80 psi cylinder is big history. |
Posted By: workky
Date Posted: August-26-2019 at 11:56am
|
I understand, and usually absolutely agree. However, the time difference in between the issues was too great, in my opinion. So i did not really connect the 2 together. The low pressure were due to the heads, or so i thought. We suspect we have a cracked piston or cracked cylinder now. I'm no longer going to bother with it until winter. It runs great, and the kids can still ride the tube. If she blows, she blows. Another question, anyone ever pulled the engine out of a Vdrive? I've done 4 direct drives, but never a V. Leave the tranny and V hooked up or just pull the engine? Anyone ever put a LS engine in a SS? My problem with the Gt40 has always been the management system. I think it sucks big time. They have way more aftermarket following for LS engines than Ford. In other words, if i pull this engine, im going to want to put a small cam in it, something better than stock. I don't think the ECU can take advantage of that or adjust itself to that. Does that make sense? I know i talk in circles, my brain is not wired correctly. Nevertheless, we will continue to use the boat until the temperature or the lake will not allow us to do so,and then the engine comes out. I guess when i exam number 6 i will determine if i should just rebuild, replace, or go crazy. |