Seeking knowledge. Goodwrench 350, 89 TBI injection, Surging

[Sonomanclature]

Greetings everyone, I am hoping some of you can help me to get this sorted out.

The Situation I have going here is this.

The base Engine is a Goodwrench crate 350 86 and prior
The injection system is stock of an 89 1500 ECU, Harness Intake and Throttle body. the ECU recieves a speed signal, but it reads double what the actual speed is.
The donor truck is a 94 s10 WITH a VCM. the VCM only reads oil PSI, and Tach readout from the Dizzy to control the Fuel pump, aswell as make the rest of the trucks electrical work.

I have 0 Vacuum leaks that I can find, I have checked all the hoses, TB gasket surface, EGR surface. The EGR Is not hooked to a working circuit, there is no vacuum supplied to the EGR solenoid, I can manually open the EGR and bog the motor at idle.

When running Warm up enrichment, it runs really well doesn't surge makes good power. as soon as it warms up it begins to surge arround 1800rmp up to 2800-3000rpm. after 3000rpm it stops surging and pulls hard.

I have ran it with out the O2 sensor connected to see if it makes a difference, there was no change in the warmed up surge. I changed the O2 out with a new Bosch unit and It didn't seem to make a difference either.

I have been running at arround 4° advance, as this is where it seems to be running best, as far as feel goes. I dont have a way to datalog yet, but I do have an Actron scanner that can do Live data.

I have been having this issue since my swap a month and a half or so, and really am trying to avoid causing damage to the engine. I do have a Carb, intake, small base HEI dizzy on deck If i cant get this sorted out, but would really like to keep the EFI setup. Unfortunately I cannot afford to buy an EBL setup at this time, Its something I have been looking into, but isn't int he financial cards any time soon.

Any help is appreciate-.

Thanks in advance


Pic of said project

[PJG1173]

welcome, glad to see you found your way over here. When you say vcm are you talking about the black box under hood computer? also it would help to know what the service number of the computer you are working with (the one running your engine) and the BCC. as for datalogging you can make your own cable (if your cheap like me) or purchase one from moates.net and use tunerpro. most people on here use tunerpro and can assist you when you post up a log. chances are that goodwrench motor has different fuel requirements than what that other setup came from. I assume that the 89 was a 350 also?

Oh and take that carb and dizzy and pitch it. once you get into tuning you won't want to go back.

[Sonomanclature]

thanks for the speedy reply,

Yes the stock black box under the hood is still there, but It only controls the Instrument cluster, Fuel pump relay, and the ABS that doesn't work any way.

The ECU for the engine is a 7747, I don't know the BCC off hand I can look tomorrow.

I haven't been keen to the Idea of back stepping from what I already have. But Always have a backup plan, just in case. Id really like to have it tuned properly and maybe pick up a few mpg as well.


Edit, nice to see a semi familiar name.

[fastacton]

I'm assuming that this wasn't a factory TBI truck? Have you checked fuel pressure? Too much pressure could cause problems similar to these and it's something to verify before you get started tuning anyway.

For the VSS problem, it sounds like you might have a 4000ppm signal when you need a 2000ppm. If you can find a 2000ppm output, that'd be ideal. But if you can't, maybe you can wire up a DRAC or VSSB to the same signal your VCM is getting the speed from and wire that to the ECM. I don't know for sure that that would work and someone correct me if that sounds wrong.

[Sonomanclature]

Yes and no on the Factory setup, It was a Factory TBI 5 speed truck, but being a 94 It has its own Engine/tranny combo VCM. It was only use with a TBI 4.3 with a 5 speed, in 94/95.

the fuel pressure holds at 11.5-12 PSI at idle and WOT. as per my fancy gauge

[fastacton]

I like the gauge location! Finding out the BCC and doing some datalogging is probably your next step. I've ran a VSS showing double the speed with a 7747 without any surging issues in the past, but it could still be worth grounding the park/neutral wire and seeing if that affects anything (provided it's a BCC for an automatic).

[PJG1173]

that 7747 should be all you need. ditch the VCM and install a DRAC/VSSB run one output to the speedo and the other to the 7747. I doubt the speedo has anything to do with the surging.