Timing, ECT, or ?

I recently got my 84 SVO running for the first time in over 5 years. The mods I have so far are Brown tops, adjustable FPR, LA3 EEC, Bob log, 3" exhaust, 3G Alt, aluminium radiator, Gillis valve, and Walbro 255. Also have a rebuilt T3 and a new Ron Francis wiring harness installed.

I set the TPS to .96 and confirmed that is has no dead spots with my analog volt meter. At this point I was able to drive the car around the block but it was running very poor. Smoking slightly but it seemed like it was running rich or maybe had a blown head gasket or something (may have just been the dust burning off). Next I checked the compression, fearing the worst, but surprisingly showed 150 in every cylinder.

I run codes on the car and I got 61 (ECT sensor low) 81, 83, and 84, not caring about the 80's codes as I do not have EGR in place. I purchased a new ECT sensor because the old one was in pretty bad shape. I just replaced to ECT with the duralast brand and think this may be the problem however I wasn't able to get a motorcraft brand at any of the local parts stores nearby. No change in test drive results

I then confirmed the timing was set correctly and it showed 10* BTDC with the spout unplugged. When the spout is plugged in it jumps to 20 BTDC and seems to return to idle normally. Car did not improve after test drive.

Next I bought a fuel pressure tester and taped it to the windshield but the car really isn't able to accelerate enough to see a noticeable change in pressure. Also the pressure when at idle is spot on 39psi and again at this point the car idles fine.

At this point I thought it might be the TFI module and I just happened to have a spare distributor with TFI still intact. Couldn't get the TFI off the distributor on the car so I pulled the whole thing. After I replaced the distributor and set the timing and get the same results.

So I did some searching and found that the ACT or IAT should be run with an LA3 EEC and the new harness instructions say that it should be strongly considered although there are many people that say it does nothing what so ever. After the ACT was plugged into a coupling between the intercooler and the throttle body the car idles at 2,000 RPM so I thought I'd check the timing and sure enough it was off for some reason? This time with the spout unplugged at 10 BTDC it goes to 30 BTDC when I plug the spout connector in? Correct me if I'm wrong but I think it's supposed to be 20 BTDC with the spout connector plugged in?

Sorry for the long post but I know this car is close to running like it should and I need some fresh thoughts about what to do next.

!0 base timing will add 10-20 degrees with SPOUT connected, depending on Premium/unleaded mode setting. This is normal and expected.

You mention 39 PSIG FP at idle - with vac line connected? It should go down by the amount of manifold vacuum if the vac/pressure hose is connected to the FPR. Assuming 10" vacuum, you should see ~34 PSIG at idle.

Could you be a bit more descriptive of “running very poor” symptoms?

Have you removed and cleaned the VAM? If not, give that a try. Are you getting any smoke out of the exhaust when driving? If so, what's the color?

Did you pull the codes again to confirm the new ECT is providing the correct info now?

When you change the fuel pump, did you replace the resistor wire and remove the inline pump.

What I meant by running poor was it would not accelerate like it should, just seemed like it wasn't getting enough fuel or there was a vacuum leak. After doing the pressure test/leak test and sealing the leaks it runs noticeably better. I tested the ECT sensor and got 4.5v but IDK what the range should be, obviously it's not within the range it needs to be due to the codes I'm getting.

I ran KOEO codes again after I reset the EEC by taking the negative battery terminal off and touching it to the positive terminal for about a min and got the same as before 61, 81, 83, and 84. I also ran KOER codes and got 21, 34, 75, and 77. I think I need to replace the ECT sensor? Fuel pressure was fine on the test drive.

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Originally Posted by Mike S

Have you removed and cleaned the VAM? If not, give that a try. Are you getting any smoke out of the exhaust when driving? If so, what's the color?

Did you pull the codes again to confirm the new ECT is providing the correct info now?

When you change the fuel pump, did you replace the resistor wire and remove the inline pump.

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I swapped vams out early on in my attempt to diagnose the issue. Both VAMs are the bigger size as I know my setup requires it but there was no change when I swapped them out. Still getting ECT codes and the resistor wire has been bypassed some time ago. I have had the single intank pump walbro 255lph pump for a while now.

Quote:

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Originally Posted by MikeFleming

!0 base timing will add 10-20 degrees with SPOUT connected, depending on Premium/unleaded mode setting. This is normal and expected.

You mention 39 PSIG FP at idle - with vac line connected? It should go down by the amount of manifold vacuum if the vac/pressure hose is connected to the FPR. Assuming 10" vacuum, you should see ~34 PSIG at idle.

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With FPR vac line connected it is reading 39 PSIG, when I disconnect it however, it drops to 34 PSIG...is that what you're talking about?

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Originally Posted by SVOKEV

With FPR vac line connected it is reading 39 PSIG, when I disconnect it however, it drops to 34 PSIG...is that what you're talking about?

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Do you have that backwards?

It should be 39 when there is no vac or pressure applied to the port on the FPR, exposed to atmosphere. WITH vacuum of an idling engine (assuming 10-12" Hg) it would be 34.

If FP INCREASES when vacuum is applied, it is defective and should be replaced.

Have you put a vac/pressure gauge on the vacuum tree on the firewall to see what manifold pressure is at idle?

If you are still getting the ECT code with a new one installed, then you have a wiring issue or a pin issue when you did the LA3 swap.