running on 2 cylinders....grrr
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vwfye
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running on 2 cylinders....grrr
well i'm hoping it is just the FI acting up and that i have a bad wire somewhere... started out with a very mild surging sensation on the freeway home the other day. got to the house and pulled in the drive and it refused to idle. the next day it barely ran. smells of fuel in the oil. i've been away on an emergency and just got back home last night. i'm hoping i have a broke or grounded wire somewhere. it is definitely running on 2 cylinders. oh joy...
Notchback mid-engine speedster
Little Giant Killer 3
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david58
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What kind of FI is it?vwfye wrote:is anyone stateside interested in swapping their t4 dual carb set up for my complete FI set up?
Hot, humid air is less dense than cooler, drier air. This can allow a golf ball to fly through the air with greater ease, as there won't be as much resistance on the ball.
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raygreenwood
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Think about this.....if you have fuel in the oil....and you are not firing on two cylinders......its an ignition problem. The fuel is getting in the oil because its not getting burned. Its most likely not a fuel injection problem. Doorstops....uh...I mean carbs...are a step backward even from D or L-jet.
Its common that you could have loss of two cylinders firing due to a bad cap or rotor, bad wires etc. Yes...they can just crap out.
Also, on the off chance that it is something injection related, check:
The trigger points
The injector plugs
The injector ground bundles under the plenum.
If you happen to pull injector plugs off onw by one to find what cylinders are not getting fuel....if thats the case.....and they are on the same side of the engine, its a ground or ignition problem. If they are diagonal, its a ground or trigger plate/plug problem. Ray
Its common that you could have loss of two cylinders firing due to a bad cap or rotor, bad wires etc. Yes...they can just crap out.
Also, on the off chance that it is something injection related, check:
The trigger points
The injector plugs
The injector ground bundles under the plenum.
If you happen to pull injector plugs off onw by one to find what cylinders are not getting fuel....if thats the case.....and they are on the same side of the engine, its a ground or ignition problem. If they are diagonal, its a ground or trigger plate/plug problem. Ray
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vwfye
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raygreenwood
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Ok....there are about 36 wires in the whole system. If its running at all and just not firing on two cylinders then it is probably a ground. The injectors are batch fired on L-jet....all four at once. If any are firing then the system is working....but you most likely have bad grounds to one or more. In D-jet...the injectors fire in pairs, like 1 & 3 and 2 & 4. The grounds for these meet up on the case centerline under the plenum.
I recommend that with the engine off you pull all four injector plugs. Mount one probe of the voltmeter on the ground bundle and check both connectors in the injector plug with the other probe. At least one should "beep"/make connection on each plug. If not...check that wire back to the ECU and check for cracks in between...and make sure the case end is securely crimped and tight.
Also.....are you sure it is firing on two cylinders?....or just acting like it is.
Its common that a simple vacuum leak can run you so rich that the power loss feelss like running on two....and will put gobs of fuel in the oil. Also check the old start valve for leakage and the flap for sticking.
Also check the CHT reading hot and cold, the CHT conection and teh resistor packs mounted on the firewall.
Lastly...and this is common and causes the "feels like its running on two cylinders" syndrome.....but check the ground braid wire between the breaker plates in the dizzy. Its common that a bad connection here causes misfires during vacuum advance. Ray
I recommend that with the engine off you pull all four injector plugs. Mount one probe of the voltmeter on the ground bundle and check both connectors in the injector plug with the other probe. At least one should "beep"/make connection on each plug. If not...check that wire back to the ECU and check for cracks in between...and make sure the case end is securely crimped and tight.
Also.....are you sure it is firing on two cylinders?....or just acting like it is.
Its common that a simple vacuum leak can run you so rich that the power loss feelss like running on two....and will put gobs of fuel in the oil. Also check the old start valve for leakage and the flap for sticking.
Also check the CHT reading hot and cold, the CHT conection and teh resistor packs mounted on the firewall.
Lastly...and this is common and causes the "feels like its running on two cylinders" syndrome.....but check the ground braid wire between the breaker plates in the dizzy. Its common that a bad connection here causes misfires during vacuum advance. Ray
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vwfye
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the other day i cleaned up the dizzy, looked for broken wires, checked the points, cleaned the plugs and fired it off with the same rough running results. shut it off frustrated and walked away.
today, i had to move the car and started it hoping to limp it to a new spot. it started and ran really rough... i kept my foot in the pedal and suddenly it smoothed out some and held an idle. then i decided to drive it. it ran well and accelerated like normal. the only issue is it will hunt like mad at idle now. it seems really odd that it ran the same after going through the dizzy and now all if fine.
today, i had to move the car and started it hoping to limp it to a new spot. it started and ran really rough... i kept my foot in the pedal and suddenly it smoothed out some and held an idle. then i decided to drive it. it ran well and accelerated like normal. the only issue is it will hunt like mad at idle now. it seems really odd that it ran the same after going through the dizzy and now all if fine.
Notchback mid-engine speedster
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raygreenwood
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vwfye
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okay... got the car on an exhaust sniffer today! it was way lean and that is all corrected now. no vacuum leaks but i'm still only getting 17.9mpg on the freeway at 67mph. how do i get this critter to brake the 20mpg barrier? i was at 11.2mpg last week, so this is a nice improvement, but at 40 miles per day round trip to work, i need better. thanks guys!
Notchback mid-engine speedster
Little Giant Killer 3
Little Giant Killer 3
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raygreenwood
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Here is the question. What did the sniffer tell you? Exactly. What was teh rpm that your reading was taken?
In general, all of the type 4 fuel injected engines had very low/lean factory settings for at idle running. They were very lean. In fact L-jet has the leanest idle settings requirements of them all (by the listed book figures).
But....this is NOT what you have through the driving range. The second you step on the gas...the AF ratio skyrockets.
Several things that can contribute to very rich running:
Dirty air filter (yes...just had to list it).
Vacuum leaks. At idle....these cause lean running but poor hp off the line.....which cases you to put your foot into it. You would be lucky if they didn't actually affect the fuel pressure at idle causing a rich condition via a spike in fuel pressure.
Vastly incorrect timing or inoperative advance.
Stuck, dirty faulty wide open throttle switch on the TB or TPS whichever you have.
Dirty grounds....trust me.
And the most common problem.....fuel pressure regulator.
What is commonly bad with the regulator is a non-linear operation. By this...I mean that at idle...the vacuum you are pulling is just enough to keep the regulator at idle pressure (about 28-30 psi). But.....as you add gas....it goes up and stays up.
Also if you have an automatic transmisssion, check the vacuum line to it and the regulator.
If your idle is hunting...you can have vacuum leaks that can cause rich operation in the upper ranges.
It is entirely possible that there is something up with your AFM...but you have a few more checks to go. Ray
In general, all of the type 4 fuel injected engines had very low/lean factory settings for at idle running. They were very lean. In fact L-jet has the leanest idle settings requirements of them all (by the listed book figures).
But....this is NOT what you have through the driving range. The second you step on the gas...the AF ratio skyrockets.
Several things that can contribute to very rich running:
Dirty air filter (yes...just had to list it).
Vacuum leaks. At idle....these cause lean running but poor hp off the line.....which cases you to put your foot into it. You would be lucky if they didn't actually affect the fuel pressure at idle causing a rich condition via a spike in fuel pressure.
Vastly incorrect timing or inoperative advance.
Stuck, dirty faulty wide open throttle switch on the TB or TPS whichever you have.
Dirty grounds....trust me.
And the most common problem.....fuel pressure regulator.
What is commonly bad with the regulator is a non-linear operation. By this...I mean that at idle...the vacuum you are pulling is just enough to keep the regulator at idle pressure (about 28-30 psi). But.....as you add gas....it goes up and stays up.
Also if you have an automatic transmisssion, check the vacuum line to it and the regulator.
If your idle is hunting...you can have vacuum leaks that can cause rich operation in the upper ranges.
It is entirely possible that there is something up with your AFM...but you have a few more checks to go. Ray
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vwfye
- Posts: 1010
- Joined: Sun May 21, 2000 12:01 am
Several things that can contribute to very rich running:
Dirty air filter (yes...just had to list it).-- brand new
Vacuum leaks. At idle....these cause lean running but poor hp off the line.....which cases you to put your foot into it. You would be lucky if they didn't actually affect the fuel pressure at idle causing a rich condition via a spike in fuel pressure.--- don't have to romp on the gas anymore... nice even pull through the entire pedal range
Vastly incorrect timing or inoperative advance. --- checked the timing and the action of the vacuum advance. both are fine.
Stuck, dirty faulty wide open throttle switch on the TB or TPS whichever you have. --- that was the fun part. afc was opened up and had to be adjusted as the settings through the adjuster screw were out of spec (this was done by the person with the sniffer and he was an FI specialist with VWoA). from there, it was adjusted per his manuals.
Dirty grounds....trust me. --- those were checked, cleaned and reattached as well (i wouldn't have even though of it, he did!)
And the most common problem.....fuel pressure regulator. --- this was tested the only way i could think of. we put the car in D and put a load on the engine and revved.
Also if you have an automatic transmisssion, check the vacuum line to it and the regulator.--- yes, also inspected
If your idle is hunting...you can have vacuum leaks that can cause rich operation in the upper ranges. --- this went away with the replacement of the 3/4" hose from the breather to the intake boot and caused my increase from 11.2 to 14.9 mpg before the system was gone through.
It is entirely possible that there is something up with your AFM...but you have a few more checks to go. ---the AFC (afm) was actually a replacement rebuild right before the car was parked in 97. and as mentioned above, it was rebuilt, but not adjusted.
this has been quite the learning adventure! i'm going to do a couple more tweakes to the system (as per the FI specialist) and see if i can get to 20mpg!
Dirty air filter (yes...just had to list it).-- brand new
Vacuum leaks. At idle....these cause lean running but poor hp off the line.....which cases you to put your foot into it. You would be lucky if they didn't actually affect the fuel pressure at idle causing a rich condition via a spike in fuel pressure.--- don't have to romp on the gas anymore... nice even pull through the entire pedal range
Vastly incorrect timing or inoperative advance. --- checked the timing and the action of the vacuum advance. both are fine.
Stuck, dirty faulty wide open throttle switch on the TB or TPS whichever you have. --- that was the fun part. afc was opened up and had to be adjusted as the settings through the adjuster screw were out of spec (this was done by the person with the sniffer and he was an FI specialist with VWoA). from there, it was adjusted per his manuals.
Dirty grounds....trust me. --- those were checked, cleaned and reattached as well (i wouldn't have even though of it, he did!)
And the most common problem.....fuel pressure regulator. --- this was tested the only way i could think of. we put the car in D and put a load on the engine and revved.
Also if you have an automatic transmisssion, check the vacuum line to it and the regulator.--- yes, also inspected
If your idle is hunting...you can have vacuum leaks that can cause rich operation in the upper ranges. --- this went away with the replacement of the 3/4" hose from the breather to the intake boot and caused my increase from 11.2 to 14.9 mpg before the system was gone through.
It is entirely possible that there is something up with your AFM...but you have a few more checks to go. ---the AFC (afm) was actually a replacement rebuild right before the car was parked in 97. and as mentioned above, it was rebuilt, but not adjusted.
this has been quite the learning adventure! i'm going to do a couple more tweakes to the system (as per the FI specialist) and see if i can get to 20mpg!
Notchback mid-engine speedster
Little Giant Killer 3
Little Giant Killer 3
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
If the engine is broken in...you should get an average of about 23 mpg in mixed city driving with an automatic. L-jet ...when tuned out....got 1-2 mpg less than D-jet. Some of that I suspect was mainly due to the reduced compression of the L-jet engines.
Timing, valve adjustment....and fuel pressure...are critical to performance and economy on these engines.
You should get a fuel pressure gauge. Every 1 psi of excessive fuel miture...or even excess fuel mixture at the wrong time....is roughly 3+% extra...more or less. Its very common that the stock regulators have a very wide range of accuracy/inaccuracy. An aftermarket adjustable rising rate regulator or a D-jet back-stop downstream is good for controlling fuel pressure. Ray
Timing, valve adjustment....and fuel pressure...are critical to performance and economy on these engines.
You should get a fuel pressure gauge. Every 1 psi of excessive fuel miture...or even excess fuel mixture at the wrong time....is roughly 3+% extra...more or less. Its very common that the stock regulators have a very wide range of accuracy/inaccuracy. An aftermarket adjustable rising rate regulator or a D-jet back-stop downstream is good for controlling fuel pressure. Ray
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MGVWfan
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FYI, with D-Jet, 1.8L, A/C, and an AT, I get 24 MPG at 70 MPH in the hills of beautiful East Texas loaded down with kids and gear, about 20 MPG in "mixed city driving" (means not stop-and-go madness, mostly "go", say 45 MPH and below), and crummy MPG (15-18) in heavy traffic (35 MPH and below, mostly stopping and waiting). This seems average for most folks I've talked to with T4 D-Jet. I suspect some of the injection recalibration Ray hints at for just-off-idle could help the heavy traffic figure. And yea verily Ray, my MPS is in good shape (it gets vacuum tested every month for good measure!). Idle CO readings are at spec for '73, BTW.
Lane
73 VW 412 (the Nomad, dropped valve seat land now, argh!)
67 MGB (Abingdon's Finest)
76 Plymouth Duster /6 (runs like a top)
99 New Beetle 2.0 (never gives any trouble)
04 Golf TDI (45 MPG)
09 JSW (love it, love it, love it!)
73 VW 412 (the Nomad, dropped valve seat land now, argh!)
67 MGB (Abingdon's Finest)
76 Plymouth Duster /6 (runs like a top)
99 New Beetle 2.0 (never gives any trouble)
04 Golf TDI (45 MPG)
09 JSW (love it, love it, love it!)
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
Thats just about right. I would say from all of your history here that yours is adjusted a bit better than the stock factory....you know what I mean 
.
But even still...in general a good condition factory stock state of tune will still give a general bare minimum of about 22 in the city. With the final drive gearing...both manual and automatic.....you should be seeing a bare minimum of 27-29 on the highway.
In practice...with a tightly tuned 411/412.....24-26 city is not hard. 30-34 mpg on the highway is the easy highway flipside to that depending on load and weather.
With a tightly tuned high compression engine....36-38 mpg is not uncommon in the sedans.
This is why I KNOW....that there is more to do in tuning vwfye's car. No sweat. It will get there. Ray
.But even still...in general a good condition factory stock state of tune will still give a general bare minimum of about 22 in the city. With the final drive gearing...both manual and automatic.....you should be seeing a bare minimum of 27-29 on the highway.
In practice...with a tightly tuned 411/412.....24-26 city is not hard. 30-34 mpg on the highway is the easy highway flipside to that depending on load and weather.
With a tightly tuned high compression engine....36-38 mpg is not uncommon in the sedans.
This is why I KNOW....that there is more to do in tuning vwfye's car. No sweat. It will get there. Ray