Engine Running Issue after rebuild

MattRRT

Member
Dec 9, 2020
12
1
13
42
Charlotte NC
1987 5.0 Manual, timing chain broke after I finally had it running well

Rebuilt with an upgraded cam. Original heads with a valve kit. Gear driven timing. Newer explorer intake

Harness and A9L computer out of an 89 for the MAF conversion.

EGR deleted since it has a newer explorer intake. All other smog was deleted before purchase.

This is a video of how its running. And what I did with timing. If I turn the idle down much more it stalls.

HELP! I am a novice, I have really only wrenched on Toyota's and no real expirience of this level.

Thoughts? Timing? Fuel? EEC?

Timing YouTube Link
 
  • Sponsors(?)


General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,174
6,822
203
polk county florida
Watch the timing light, it flickers like the engine has a miss.
You sure the firing order is correct?
What cam did you install and why the gears and not a chain?
 

MattRRT

Member
Dec 9, 2020
12
1
13
42
Charlotte NC
Some of that is frame rate capture. I triple checked it today, the firing order is correct.

Today I purchased a test light for the ignition and when I rev it up, it misses on multiple cylinders, (2, 3, and 6) at the 2000rpm range
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,174
6,822
203
polk county florida
Start with looking at the distributor cap, the distributor can develop side play causing a random cylinder misfire, sometimes the cap will show scrape marks.
plug wires can cause random misfire too.
 

MattRRT

Member
Dec 9, 2020
12
1
13
42
Charlotte NC
So thinking about the relay code, I swapped the AC relay for the fuel pump relay ( no AC in the car anymore) and it runs MUCH better now.

Still stumbles a bit here and there so I'm gonna do the fuel filter now. We will see
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,174
6,822
203
polk county florida
The occasional stumble is usually an electrical issue, ten pin connectors (salt and pepper shakers) , plug wires, that kind of thing.
 

MattRRT

Member
Dec 9, 2020
12
1
13
42
Charlotte NC
The occasional stumble is usually an electrical issue, ten pin connectors (salt and pepper shakers) , plug wires, that kind of thing.

now it’s stumbling consistently at 2500, can accelerate through it now. I did do the fuel filter

I ordered a new injector harness, was hoping I wouldn’t need it (I’m way over budget) so I may give that a shot.

I may start checking injectors too
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,174
6,822
203
polk county florida
 

MattRRT

Member
Dec 9, 2020
12
1
13
42
Charlotte NC
I am wondering how much this has to do with it

Any car that has a 3G or high output current alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects. The 3G has a 130 amp capacity, so you wire the power side with 4 gauge wire. It stands to reason that the ground side handles just as much current, so it needs to be 4 gauge too.
 

MattRRT

Member
Dec 9, 2020
12
1
13
42
Charlotte NC
OK so I have replaced 2 relays. Reset the EEC (battery disconnect with headlights on)

It ran fine while cold, once warm it started stumbling again. The only non-smog related code is 95, secondary fuel relay.

I am going to do the check on the inertia switch that I found elsewhere on this forum.

Fuel pressure check is 45 pounds with out without the FPR hooked up to vacuum. Any thoughts?