Volvo 4.3Gi TBI headache... Volvo expert needed

[ss9940_2]

Hi all!

Last year I already opened a question about a 4.3GIPEFS but still couldn't solve the problem... So this year the problem still persists... The engine is a 2000 4.3Gi with sx sterndrive. The engine was replaced last year with a rapido longblock, along with:

- intake manifold
- exhaust manifolds & risers
- distributor cap
- tune up kit (all filters, sparkplugs, etc.)
- belt
- thermostat
- impeller

If I get to the problem: the engine bogs down while accelerating! It's running ok when idling, or on constant RPMs but otherwise it stumbles when you try to hammer it. Here's what i've already done:

- checked ECM with a tester, no errors!
- measured fuel pressure:
- 10 PSI on the low pressure side (although the manual says 6PSI+-2PSI)
- 30 PSI on the high pressure side (seems ok according to the manual)
- checked timing, everything ok

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)...

BTW this error was present BEFORE the longblock swap!

It seems i'm a bit lost... What else could I check? Could the TP sensor be faulty without triggering an error in the ECM?

Oh, another thing... I have a connector with 2 wires that doesn't go anywhere. The wires are black/white and tan/white... What is this connector for?

I'll post some pictures later on!

Thanx in advance!

Alex

 

[Don S]

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

What is the FULL model number of the engine, or the Serial Number of your original engine.

 

[ss9940_2]

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

Hi Don!

Thanx for the quick reply... The full model number is 4.3GXi-A i believe!

Thanx

Alex

 

[ss9940_2]

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

Hmmmm according to the wiring diagram, there should be a MAT sensor with black/white and yellow/white (T/Y in the manual) wire to it... Where should it be located? Is it missing?

Posting pictures below!

Thanx Alex

 

[coastalcruiser]

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

Hi
try and find the Serial number of your engine, saying it's a 4.3GI over and over won't get you any help

 

[ss9940_2]

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

Sorry, my customer sent these to me:

Number: 3869055
type: 4,3Gi pefs
and another number(?): 4012043488

Thanx

Alex

 

[Don S]

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

Disregard, different engine now. Not a 2001 GXi-A

 

[ss9940_2]

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

Hmmm strange... if I look at the wiring diagram for an EF engine, there is a MAT sensor... BUT the EFI manual doesn't mention the MAT sensor at all...

 

[Don S]

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

Yes it does, but it's called an IAT and makes note of the fact that it's not used with a TBI system.

 

[ss9940_2]

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

Yes it does, but it's called an IAT and makes note of the fact that it's not used with a TBI system.

...only found on the 7.4 GSi and 8.2 GSi model engines... So looks like I'm going into the wrong direction... What else could be causing such behaviour?

The pressure on the low pressure side is a bit high, but that can't be it, can it?

Alex

 

[Don S]

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

Actually, that spec was changed. It's now 8 +-4 psi. So the pressures are fine. have you done all the tests on page 5-8 of the diagnostic manual?

 

[ss9940_2]

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

Actually, that spec was changed. It's now 8 +-4 psi. So the pressures are fine. have you done all the tests on page 5-8 of the diagnostic manual?

Preliminary Checks
? Perform the important preliminary checks as described at
the start of Symptoms Section. *CHECK*

Fuel System Checks
? For water contaminated fuel, and dirty or restricted fuel
filter *CHECK*
? Fuel pressure. Refer to Chart A-4 or A-5 in Diagnoses
section. *CHECK*
? Worn throttle linkage *CHECK*
? Check Fuel Injectors. ??? HOW TO DO THAT ???

Ignition System Checks
? IC system for proper timing and advance *CHECK*
? Spark plug wires for being faulty *CHECK*
? For RPM reduction mode
? Spark plugs for being fouled or improper gap *CHECK*
? Integrity of primary and secondary wiring, IC module,
pickup coil, and distributor. *CHECK*

Sensor Checks
? TP sensor - For binding, sticking, or salt corrosion. TP
sensor voltage should increase as throttle is moved toward
Wide Open Throttle (WOT). *CHECK*
? TP sensor - 5 volt reference for open circuit from TP sensor
connector terminal ?A? to J2-19. DTC 22 may be set. *CHECK*
? TP sensor circuit for open or grounds from TP sensor connector
terminal ?B? to J2-26. DTC 21 may be set. *CHECK*
? MAP output voltage check, Chart A-8, Diagnoses section. *NOT YET*
? ECT for shifted value. * ??? HOW TO CHECK ??? *

Additional Checks
? Proper alternator output voltage * NOT YET *
? For faulty or incorrect thermostat *NOT POSSIBLE*
? Throttle linkage for sticking, binding, or wear *CHECK*
? Intake valves for deposits. * NO WAY, IT'S BEEN DOING IT SINCE SWAP *

 

[Don S]

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

? MAP output voltage check, Chart A-8, Diagnoses section. *NOT YET*

That's odd, I would have thought that would have been one of the first things to check.

Circuit Description
1 The MAP sensor measures the change in the intake
manifold pressure, which results from engine load
(intake manifold vacuum) and RPM changes, and converts
these into a voltage output. The ECM sends a 5
volt reference voltage to the MAP sensor. As manifold
pressure changes, the output voltage of the sensor also
changes.
By monitoring the sensor output voltage, the ECM calculates
the manifold pressure. A low pressure (low voltage)
signal will be about 1 to 2 volts at idle. A high pressure
(high voltage) signal will be about 4 to 4.8 volts at
Wide Open Throttle (WOT).
The MAP sensor is also used, under certain conditions,
to measure barometric pressure, allowing the ECM to
make adjustments for altitude changes. The ECM uses
the MAP sensor to control fuel delivery and
ignition timing.

 

[ss9940_2]

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

Ok will check and report back... If I recall correctly, I did that last year while installing the engine... But will get back with fresh data... Still, isn't it strange that there is no error code?

Alex

 

[Don S]

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

Still, isn't it strange that there is no error code?

The sensor gives different readings for different amounts of engine vacuum and changes all the time. The computer doesn't know if the readings are false or not. The only thing that will set a code is if it's open or shorted, not just off in what it reads.
people always try to read to much into the codes.

 

[Tail_Gunner]

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

Some overly simple things

1. Rich...check for sooty plugs that tbi is a 454 tbi and can flood a 4.3 quickly

2. Lean llght brown or white plugs... Injectors dirty....Take a neon light or led and check the spray pattern, that type of light will allow you to see the spray pattern clearly and drips you cannot see under normal lighting conditons or a misformed spray pattern

3. You may have a timing issue or a intermittent ignition system issue somewhere

4 The fact that it run's well at a even load...not every time but a good majority of the time stumbling under a load is a timing issue or ignition issue

Do you have the necessary software to check your ign knock counts???

 

[ss9940_2]

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

Hi all!

SUCCESS! Seems it's the MAP sensor... The voltage reads 1,2 +- 1V no matter what you do with the throttle! Every now and then it seems to work (voltage jumps up), but then it returns to 1,2V... Now will this do? http://cgi.ebay.com/ebaymotors/SMP-STANDARD-AS165-Map-Sensor-_W0QQcmdZViewItemQQhashZitem5ae084407dQQitemZ390313820285QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

The number of the part is 3850396, correct? The part is INSANELY expensive here in Europe, around 450$!

Alex

 

[Don S]

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

Yes, 3850396 is the correct part number. Will the one in your link work? It's the correct part number and it says it's new. For that price, you might want to buy both of them.

 

[ss9940_2]

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

Both of them? What do you mean? There is only one MAP sensor...

 

[Don S]

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

Both of them? What do you mean? There is only one MAP sensor...

The guy in your ebay link has 2.