Poor Power below 2000 RPM, 1987 740 GLE

[itguy1010]

Hi all,

New to the forum but not new to Volvos.

Anyway, the vehicle: 1987 740 GLE B230F (LH Jetronic 2.2) Automatic Transmission 150Kmiles

The symptoms: Good idle, but very poor low rpm performance. Just dogs with the pedal mashed and takes forever just to get across the intersection when the light changes. After it hits about 2000 rpm its like flipping a switch and the car will take off but as soon as it changes gears the rpm drops and its back to very low power.

Recent work: Replaced head gasket (showed signs of leaking coolant near #4cyl near the exhaust manifold) and timing belt (since it was so easy to do at the time). While the intake manifold was off I noticed a completely crumbling engine harness and replaced that as well. After putting all back together I had problems setting base idle and replaced the TPS and cleaned the TB just for grins. The O2 sensor is practically new but I plan on changing it again here in a few thousand miles just because of possible silicon contamination from the new head gasket.

The car ran well before all this but with the coolant leak and other upcoming issues I figured I'd just get it all done now.

Anyway, after having some initial problems getting the base idle set I have checked the timing. Yes, the new timing belt is on correctly (confirmed it twice) and I can easily set 12 deg. BTDC on the harmonic balancer marks with a timing light. I have read approximately .52 volts between pins 2 - 5 on the ECU terminals when engine is hot so I believe the ECU is getting good ECT data. I should say that my first engine harness that I put in had some issues (now on a second one that works fine) and I am worried that I may have damaged my ECU but now this seems like a fuel issue and I'm wondering if I should change my Fuel Pressure Regulator or test it. I don't have a gauge to test the pressure with. When setting base idle I've had to crank the idle adjustment knob (the black plastic one) almost all the way in to get to 750RPM. That seems a little weird too. Possibly related? I have tested the obvious radio suppression, fuel pump and fuel injection relays and all seem good. I have also checked the fuel pumps and they seem ok too. The car starts and idles great, very smooth with no stumbling. Have checked and cleaned the ground connection from the firewall to the intake manifold and all other electrical connections that I can find. All seem ok.

So, if anyone has any suggestions before I replace my ECU (I'm looking at a used one on eBay for $50.00) or FPR I'd sure be grateful to hear them.

Thanks,

Eric.

Edit: The problem actually is below 3000 rpm. And, it behaves the same way with or without the O2 sensor connected.

[jimmy57]

First cheap n easy thing to inspect is the hot/cold air door in air cleaner box. If it is open to the hose to exhaust manifold at 60 degrees or above it is not working right. If it is open to hot air side you can push the door over and use a couple of screws run through the door into the housing to hold closed to hot side.

If this is working correctly then the balancer needs to be inspected for slipping. If it slips the timing is adjusted using a mark that is wrong and timing is wrong. Insert a long bolt through the #1 spark plug hole with the piston down a ways (timing marks misaligned either direction 2 inches at least). Move engine over with socket on crank bolt slowly until it stopsagainst the bolt held in till touches the other side of cylinder. Use a 12 inch long 3/8 extension instead of bolt if you have no bolts that long on hand. Mark the damper edge with chalk, crayon, or nail polish/touch up paint where it aligns with 0 mark on t belt cover scale. Now turn engine the other way until it stops again on bolt/extension. Mark this spot on damper edge the same way.
If your damper is good the notch across balancer edge will be even distance between the marks you made. If not mark the spot half between the two and use it to set timing this one time for diagnostic purposes. Balancer should be repalced.
Are you adjusting base idle with a/c off and the test lead grounded on LH fender?

If the two things to check are good then you need to drive it and read flash codes from the diagnostic flash code lead w/o turning off the engine after the drive. The flash codes are not stored, only valid on that ignition cycle.
Let me know what color the two wires are in that two wire connector hanging off the harness at top inner fender edge a few inches in front of the upper strut housing. I think the idle test wire is blue and the other is the lambda CO setting lead. The ignition should be a second two wire connector with only one wire in it (is it read with a yellow stripe???)
To get CO indication or codes from ignition you will need an LED test light. Can't be a bulb as the signal is too low current to drive a bulb. Attach the lead to pos post of battery and probe the CO lead or the ignition code lead as the outputs are grounds.
ignition codes:
EZ-117/118K codes:

1 flash: Maximum timing retardation reached under full throttle acceleration
2 flashes: Temperature sensor fault (B230K only)
3 flashes: Maximum timing retardation reached at idle or > 3150 RPM
4 flashes: Faulty load signal from fuel injection ECU (engine at part load, not idling)
5 flashes: Insufficient advance at idle (B200E/B230E/B230K only)
6 flashes: Insufficient advance (B230K only)

The knock sensor evaluation is complete when engine is loaded and speed must exceed 3150 RPM. In other words, don't just rev it up sitting there, go drive it and then read codes w/o turning off engine.

[itguy1010]

Hi Jimmy,

Thanks for the quick reply.

I removed the hot/cold airbox assembly last year since I only drive this car in the Spring/Summer here in Michigan.

I'll do the TDC Harmonic Balancer marking procedure tomorrow and make sure that it hasn't moved. Good call.

I'm not sure about the wires on the left side fender wall for the IAC disable. My colors don't seem to match what I've been reading and when I ground any of them (I have square two-wire connector and a round single wire connector) I get no change in idle speed so I'm not sure that the IAC is actually getting shut down for my base idle adjustment. I'll post a pic of what I've got a little later this evening to clarify.

My engine (B230F) uses the older LH Jetronic 2.2 and I thought that unit didn't do flash codes. If I'm wrong then let me know and I'll get set up to check them.

Thanks again,

Eric.

[itguy1010]

SOLVED!!! (Partially)

After confirming correct crank pulley TDC indication (it was right on) I began digging deeper into what would cause the problem below 3000 RPM and began to look at the knock sensor circuit. What I found was a pushed in terminal on the knock sensor connector effectively disconnecting it from the ECU. Repaired the connector and the problem was gone.

So, thanks for looking and Jimmy, thanks for the feedback and suggestions. I'm still not sure why I can't seem to locate the right connector to ground out the idle control circuit. It seems to just idle a little high at this point (850rpm with AC disconnected) but I still have the idle speed control knob dialed in almost all the way so it appears that something is still not right with that part of the constant idle system.

I'm attaching two photos of the only connectors I can find in the area they are supposed to be for the IAC disable. They don't seem to be the right wire colors. If anyone has any other way of temporarily disconnecting the IAC control circuit to set base idle I'd sure love to hear about it.

Thanks.

Eric

P.S. In case I didn't mention it, this is a B230F with Bosch LH Jetronic 2.2 from Germany and I'm not sure if that would make a difference with the IAC wiring.

0711120648b.jpg (285.44 KiB) Viewed 2552 times

0711120648a.jpg (369.39 KiB) Viewed 2552 times

[jimmy57]

On the two wire connector you ground each lead to find the IAC service lead. The throttle may need to be cleaned and set up correctly.
I'm sketchy on the test wires, I haven't worked on a LH2.2/EZK 117 car in a dozen years or so. I worked on them every day when they were "young" cars.

[itguy1010]

On the two wire connector you ground each lead to find the IAC service lead. The throttle may need to be cleaned and set up correctly.
I'm sketchy on the test wires, I haven't worked on a LH2.2/EZK 117 car in a dozen years or so. I worked on them every day when they were "young" cars.

Ok, I'll try grounding each one independently and see what I get. Should there be a noticeable change in the engine rpm when I ground the right lead? Because I've tried grounding each one and nothing really changes. I cleaned the throttle body, replaced the throttle position switch and set the new switch up according to the procedure I've found in the FAQ. Could I possibly have a bad IAC? It seems that when I turn the engine off I hear a motor whirring inside the IAC for a few seconds. Does that sound normal?

Eric

[jimmy57]

If you slip off the hose from the air hose that connects to IAC and block the fitting and the hose the engine should idle at 450-500. If it is faster then you may have linakge or stop screw setup issues and maybe microswitch adjustment issues.

[itguy1010]

Thanks again Jimmy,

I'll keep banging away at it. The good news is the car is running very well now with the knock sensor issue repaired. I can live with a slightly high idle but I will get back to the IAC issue shortly.

Spent all day yesterday working on some minor electrical issues and replacing the front upper strut mounts. My coil compressors are very old and balky and that job is a serious pain in the butt (in my opinion). Next on the list is to work on an oil leak, change the differential fluid, check the transmission tailshaft housing bushing seal and see if I can repair the supplemental AC fan.

Just want to say thanks for all the help and suggestions. What a great forum!

For now, I think we can consider the original issue (no power below 3000 RPM) closed.


Eric