Volvo 4.3Gi TBI headache... Volvo expert needed

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

...and the show goes on... Today I replaced the MAP sensor with no effect... Looks like I misjudged the faulty operation (didn't have a vacuum gauge)

So, I decided to dig deeper... I compared all the reference values from the manual with actual J1 and J2 readings (igniton on and on IDLE) and I found some different values... The one that is suspicious is the J1-10 pin on the ECM, that's the IC signal (page 78 in the service manual); it should be 1,2V when running IDLE, i was reading 0,5-0,6V... So I looked a bit further, the pickup coil resistance was 880 ohms, the resistance between J1-10 and ground was 1,368 ohms (should be between 3000 and 6000, right?)

Do you think it's the IC module? Or could the wiring be it? I also checked the voltage on the 1st terminal on the IC output (IC signal), it was the same as on terminal J1-10, 0,5-06V... What do you think?

Guess Tail_Gunner was going in the right direction... I vote for his point no. 4)...

Thanx

Alex

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Could the IC module be from another engine perhaps? A Merc? I wouldn't be surprised to find out the old engine was assembled from different parts...

And no, I cannot check the knock counts...

 

[Tail_Gunner]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

""""The engine seems to get too much fuel when you accelerate that's why it stumbles... If i remove the TP sensor and leave it be, it accelerates far better (less fuel cause the ECM thinks that the throttle is on IDLE)...


There has been a lot of fuel issues lately....Seems like the 70's all over again that was the first time alochol was introduced into gas motors....

So do this take a neon light and check the pulse rates of the injectors...No drips and a nice conical spray pattern....They may need cleaning...You may check the injector types themselves...aka on top or the injector plugs there should be a colored coded plastic sleeve what colors do you have on the pins??

Thats a 454 GM TBi you may need to find someone to clean it up if not thats a huge varicance with your IC

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

The pins are orange/orange, the number is 25170301 ACR 0129 GM; the spray is conical, but the engine is smoking black and there is a loot of soot coming out of exhaust...

Alex

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

... And the saga continues... I just got my hands on the boat yesterday and it's STILL having the same symptoms... It just bogs down when you want to rev it up fast... What I already checked:

- fuel pressure is 30PSI on the high pressure side
- moving the distributor doesn't really have any effect or very little
- fuel consumption was terrible (during the season)
- all the sparkplugs are black
- i checked the pulse with a neon light; there is a slight drip, barely noticable (in the conical spray)
- if you suddenly open the throttle to WOT, it bogs and stays at around 3000, won't rev up
- if you open the throttle slowly, it works quite well, no bogs
- changed MAP sensor with no effect
- checked the TP sensor with a DVM, checks out ok
- replaced the IAC sensor, no trouble there


- Still thinking about the coil or the module (see my last post) - would it be possible that the computer calculates the pulses wrong cause of a faulty pickup coil?
- Could a faulty intake manifold gasket cause any trouble?
- I'll clean the injectors regardless if they're causing any trouble or not...

Thanx

Alex

Alex

 

[Tail_Gunner]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

... And the saga continues... I just got my hands on the boat yesterday and it's STILL having the same symptoms... It just bogs down when you want to rev it up fast... What I already checked:

- fuel pressure is 30PSI on the high pressure side
- moving the distributor doesn't really have any effect or very little
- fuel consumption was terrible (during the season)
- all the sparkplugs are black
- i checked the pulse with a neon light; there is a slight drip, barely noticable (in the conical spray)
- if you suddenly open the throttle to WOT, it bogs and stays at around 3000, won't rev up
- if you open the throttle slowly, it works quite well, no bogs
- changed MAP sensor with no effect
- checked the TP sensor with a DVM, checks out ok
- replaced the IAC sensor, no trouble there


- Still thinking about the coil or the module (see my last post) - would it be possible that the computer calculates the pulses wrong cause of a faulty pickup coil?
- Could a faulty intake manifold gasket cause any trouble?
- I'll clean the injectors regardless if they're causing any trouble or not...

Thanx

Alex

Alex

i checked the pulse with a neon light; there is a slight drip, barely noticable (in the conical spray)
- if you suddenly open the throttle to WOT, it bogs and stays at around 3000, won't rev up
- if you open the throttle slowly, it works quite well, no bogs

If that was a carb one would think a accelerator pump which is a fuel dileivery issue..the drip indicates stuck injectors pershaps clogged..at the base of the injector there are screens..changing the dist will not work with mefi the software controls the rpm igntion timing. Under power you can take a brake cleaner and spray it around the intake or vacum points if the engine slows...thats a leak...Or you can use starting fluid and do the same...Not recomended though it could be a explosive event.

http://www.witchhunter.com/ great cleaning service they also supply you with data results and you do have the right injectors A little note as said before you do have a 454 tb and injectors... now couple that with a mefi system and its very easy for that little 4.3 to run rich it would not take much for that system to run rich...It runs on the a very rich burn right out of the box..That is its tuned for a rich burn

 

[Glastron_V210]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Are you really using a 454 throttle body on a 4.3? If this is the case, and you haven't replaced the injectors to the 4.3 size (smaller) then this explains your rich condition stumble. When you open the throttle a change in tps or a big enogugh change in MAP signal will kick in acceleration enrichment (Like an accel pump on carbs) and drown that engine, 'cause the shot is for a 454, not a 4.3. This would be totally expected. Disconnecting the tps will reduce the accel enrichment (not eliminate it because the map also kicks it in). You would expect to be pig rich across the board because there is no 02 sensor for corrections to take place. To be honest, I'm surprised it runs at all!

In short, get 4.3 injectors and you will be in good shape. The throttle body is the same as the automotive one, so order up some 1992-1994 Jimmy/Blazer/S10 injectors and go boating!

I check spray pattern with a timing light...hook it up to #1 cylinder and fire the strobe at the injectors. Works well. These injectors are notorious for clogging up.

Last note, on cars we run about 14psi nominal. I'd like that a bit more than 8psi for sure. The spray pattern gets better with more pressure. There is no fueling correction, so more pressure = more gas! There are pages online to convert your regulator (on the TB) to adjustable, then you can play with it all you want.


Last note: What is the ecm from? The tuning will likely be a bit different timing/fueling for a 454 than a 4.3, so you may want to get a chip made up for a stock 4.3 as well.



Chay

 

[Tail_Gunner]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Are you really using a 454 throttle body on a 4.3? If this is the case, and you haven't replaced the injectors to the 4.3 size (smaller) then this explains your rich condition stumble. When you open the throttle a change in tps or a big enogugh change in MAP signal will kick in acceleration enrichment (Like an accel pump on carbs) and drown that engine, 'cause the shot is for a 454, not a 4.3. This would be totally expected. Disconnecting the tps will reduce the accel enrichment (not eliminate it because the map also kicks it in). You would expect to be pig rich across the board because there is no 02 sensor for corrections to take place. To be honest, I'm surprised it runs at all!

In short, get 4.3 injectors and you will be in good shape. The throttle body is the same as the automotive one, so order up some 1992-1994 Jimmy/Blazer/S10 injectors and go boating!

I check spray pattern with a timing light...hook it up to #1 cylinder and fire the strobe at the injectors. Works well. These injectors are notorious for clogging up.

Last note, on cars we run about 14psi nominal. I'd like that a bit more than 8psi for sure. The spray pattern gets better with more pressure. There is no fueling correction, so more pressure = more gas! There are pages online to convert your regulator (on the TB) to adjustable, then you can play with it all you want.


Last note: What is the ecm from? The tuning will likely be a bit different timing/fueling for a 454 than a 4.3, so you may want to get a chip made up for a stock 4.3 as well.



Chay

That might work for automotive but his system is delphi marine. The 454 tbi is stock as are the injectors..It uses a open loop mefi 3 speed density everything is mapped out and they all run quite rich. Below is a example of mefi


Engine load is primarily determined by sensing the current engine speed and reading the manifold pressure via the manifold absolute pressure (MAP) sensor (this is similar to old-fashioned vacuum signal). The MEFI module uses RPM and MAP to select data from a table with rows and columns of numbers that represent injector pulse width values (milliseconds of on-time). When the ECM needs to know how much fuel to deliver it reads the MAP and RPM, then it refers to the corresponding row and column in its fuel table to obtain the correct injector pulse width, also known as the ?base pulse width?. Once this pulse width value is obtained there are adjustments made to it based upon other engine operating conditions, however MAP and RPM are the main factors involved in selecting the base value.

The engine?s spark advance is also selected in similar fashion. Again, there is a table in the ECM ?s memory with rows and columns of numbers that specify degrees of advance. The desired advance value is chosen based upon RPM and MAP. Once the desired spark advance is obtained, other operating conditions are evaluated and used to adjust the value.

The conditions my Turn Key LS2's MEFI-4 system uses to adjust base pulse width and base timing include throttle position, coolant temperature, manifold air temperature, air/fuel ratio (exhaust O2), and knock detection. The complete list of Turn Key LS2 sensors and what they sense and report is as follows:

MEFI-4 Inputs

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Hi and thanks for the info... The only trouble is that those guys from http://www.witchhunter.com/ don't ship internationally... Since I'm from Europe, that would represent a minor problem Can you recommend someone that does ship internationally?

BTW, there isn't a shop in EU (at least one that i know of) that could do such a thing... So shipping to US is a *must*

I already replaced: ignition module (still no change), cleaned the injectors myself with carb cleaner and a homemade reverse flow device (again, no change)
I'm also replacing: sparkplug wires, sparkplugs, cap, rotor once again...

Thanx in advance

Alex

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Oh, and another question... Should the ign timing be set to 8 deg BTDC in base timing mode (according to the manual) ?

Thanx

Alex

 

[Don S]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Oh, and another question... Should the ign timing be set to 8 deg BTDC in base timing mode (according to the manual) ?

Uhhhh, Yes? How else whould you do it?

 

[Glastron_V210]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Tailgunner, maybe he can't modify the code, but he can and should change injectors and get that 30psi fuel pressure reading under control. His presure reg is toast, or the return is blocked.

He will not have success otherwise.

You have correctly identified the operation of an open loop ecm. Any open loop ecm operates the same way (With a MAP system anyway). I can make a gm ecm look like this really easily, by blocking closed loop operation. It's a very typical control strategy.


Chay

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Hi all!

Don: Sorry, i found your thread about setting the ign correctly but the only change is that you hook it up to B+ after the engine started!

Looks like this problem is common and persistent... I looked around a bit and found this thread:

http://www.marineengine.com/boat-fo...olvo-Penta-50Gi-running-rich-and-soot-buildup

that has very similar problems that i have... Plus, there was no solution found

Another thing that could help out: when the engine is cold, you can fully open the throttle and the engine won't bog down, but when it's warmed up, and you try to rev it up fast, it bogs down and sometimes backfires...

I'm going to change the cables, cap, rotor and plugs and look for a change... Any more suggestions are welcome

Alex

 

[Tail_Gunner]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Tailgunner, maybe he can't modify the code, but he can and should change injectors and get that 30psi fuel pressure reading under control. His presure reg is toast, or the return is blocked.

He will not have success otherwise.

You have correctly identified the operation of an open loop ecm. Any open loop ecm operates the same way (With a MAP system anyway). I can make a gm ecm look like this really easily, by blocking closed loop operation. It's a very typical control strategy.


Chay

High Pressure System Checks
The single most important diagnostic tool is a fuel pressure
gauge. Attach it to the high pressure pump test valve
and crank or run the engine. Look for the pressures
specified.
? 7.4 Gi, GSi and 8.2 GSi Models: 39 ? 3
PSI (269 ? 21 kPa)
? 4.3 Gi, 5.0 Gi and 5.7 GSi Models: 29 ? 2
PSI (200 ? 13,8 kPa)
The high pressure pump and its associated system components
are operating properly if the pressures are correct.
If they aren?t, review the items listed under High
Pressure System Components and check their operation

30 psi is dead on

 

[Tail_Gunner]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Hi all!

Don: Sorry, i found your thread about setting the ign correctly but the only change is that you hook it up to B+ after the engine started!

Looks like this problem is common and persistent... I looked around a bit and found this thread:

http://www.marineengine.com/boat-fo...olvo-Penta-50Gi-running-rich-and-soot-buildup

that has very similar problems that i have... Plus, there was no solution found

Another thing that could help out: when the engine is cold, you can fully open the throttle and the engine won't bog down, but when it's warmed up, and you try to rev it up fast, it bogs down and sometimes backfires...

I'm going to change the cables, cap, rotor and plugs and look for a change... Any more suggestions are welcome

Alex

Another thing that could help out: when the engine is cold, you can fully open the throttle and the engine won't bog down, but when it's warmed up, and you try to rev it up fast, it bogs down and sometimes backfires...


Ok that is a contradiction....""A mefi 3 will run rich when cold""and it runs well there.... and your saying it "bogs and misses" when warmed up at high rpm???? Has this always been the issue?

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Don't know if this issue has came up lately or if it was always present... Just noticed it while testing the other day... Why? Does it mean that the ign is incorrect when warmed up? The backfire should mean that it is running lean, shouldn't it? I'm completely confused

Alex

 

[Tail_Gunner]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

First a mefi 3 does have a cold enrichment mode and your engine runs fine until it warm up why is that.

Here you state Another thing that could help out: when the engine is cold, you can fully open the throttle and the engine won't bog down, but when it's warmed up, and you try to rev it up fast, it bogs down and sometimes backfires

Here you state: The engine seems to get too much fuel when you accelerate that's why it stumbles... If i remove the TP sensor and leave it be, it accelerates far better (less fuel cause the ECM thinks that the throttle is on IDLE

V210: Disconnecting the tps will reduce the accel enrichment (not eliminate it because the map also kicks it in). You would expect to be pig rich across the board because there is no 02 sensor for corrections to take place. To be honest, I'm surprised it runs at all!
210

I would visit the tempature sending unit and the TPS again that is where your problem is.....and maybe a stuck injector or a combination of all three. Do you know how hot of thermostat you are running...Hmm you are running a thermostat arent you..


http://pirate4x4.com/tech//billavista/MEFI/MEFI-4 DTC's.pdf

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Hi all!

Today i took another look at the engine... I replaced the cables and sparkplugs (the engine calls for NGK BPR6FS (short reach) but what i found was NGK BPR6EFS (long reach)) and the engine started to act far better when revving it up; but nevertheless it still stumbles a bit. I looked with a LED light again and noticed a drip on one of the injectors... So what i need to do now is ship them to the US to a shop to get them professionally cleaned up & calibrated...

Since the guys from www.witchhunter.com don't ship internationally, could you reccommend another serious shop? Or could I find one in the EU? England perhaps?

Thanx

Alex

 

[Tail_Gunner]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Ok if that is a pefs gi it has vortec heads....113 casting's with fulcrum rockers which are vortec heads....and does call for long reach plugs...But i will admit after using them (long reach) also the engine seems a bit lazy if thats a desription..I have the same engine

That would be intresting to find i was using the wrong plug....:redface:

 

[ss9940_2]

Re: Volvo 4.3Gi TBI headache... Volvo expert needed

Hmmm that's odd.... The manual for the EF engine states that the 4.3Gi model should use CHAMPION RS12YC (short reach) or AC-MR43LTS (long reach)...