throttle tip in issue

[Tjohnson]

im having an issue with my truck.

it has a freshly built 302, with a large cam, and im having an issue with throttle tip in. it will lean out and pop and surge.

in my log the pulse width jumps and drops. i just dont know whats causing it.

the log starts at idle, gets put in gear, and then roll into throttle and try to accelerate.

thanks in advance

[slow_hemi6]

I don't know where your VE table came from but that table is going to be undrivable for sure. It has 28 in every cell up to 3500rpm.
2nd issue is your vacuum range is not going to work well with speed density. I am seeing at best 6.5in hg but more often around 3in hg. I would like to know those cam specs.
You should also calibrate your TPS.

[rickb794]

The vacuum might come up if it gets enough fuel.

The spark table could use some work too.
Have you verified spark timing is the same as commanded?

Why is EGO disabled?

[Tjohnson]

i attached the wrong msq.

ego control is off because ive only had issues with it in every other car im running ms2 on

this is my cam specs. http://www.compcams.com/Company/CC/cam- ... d=903&sb=2

timing table is 302 base tune table from diyautotune

attached is the msq im actually using. it still needs work but this issue is making it hard

timing matched commanded

[slow_hemi6]

Auto with hi stall or manual?

[Tjohnson]

2500 stall c6

[kjones6039]

That's still a mighty wild looking VE table! IMO

ego control is off because ive only had issues with it in every other car im running ms2 on

I'm kind of interested in what those issues might have been...........

Ken

[slow_hemi6]

I think you are about 1000 short on stall. Comp are quoting 8in hg for a xr294hr on a 350 @ 1000rpm so you should be similar. I would try a little more timing @ idle and see if you can improve on that 6.5in hg. The engine goes into a funk when you drop it into gear and rpm drops to around 600 and you have about 3in hg vacuum. It is crying out for an IAC to pick the revs back up and regain some vacuum. As I said before your resolution on the speed density table is going to make it hard to try and tune transisitions.

[turbo conversion]

For what it's worth the spec sheet recommends manual transmission and says NOT FOR EFI.

Also it shows to be for a 351 not a 302, not sure why but the manufacturer has a reason for this.

I agree with slow_hemi6, with automatic transmission for best performance you will need the extra stall (been there don that).

David

EDIT: word

[hybrid]

I'm assuming the 302 is a ford engine.
Whether it's Windsor or Cleveland, the 351 cam should work fine in a 302.

The 351W had a different firing order than the common 302 (and 289), but the 302 HO had the same firing order as the 351, which is meant to be friendlier to the crank.
So I don't think the cam is a real issue.

I have also found that generally when they say not for EFI, they mean factory EFI engines. In this case it may be that the cam characteristics won't play nice with the factory computer. Which means in the MS2, it might need hybrid Alpha-N or something to run properly.

[turbo conversion]

So, to make the 351 cam work in a non HO 302 all you need to do is chance the firing order?

David

[whittlebeast]

You have way too much AE. You are putting out the fire with excess fuel.

[slow_hemi6]

I noticed the AE triggering but also that it wasn't driving AFR overly rich either, which made me look at the VE table. I think if he can stabilize the idle and work on getting some actual resolution into the transitions he won't have so much false triggering to deal with. Can always disable AE and work on idle and slow transitions first, then bring AE back and adjust.

[Tjohnson]

I am thinking it's too much ae as pulsewidth almost doubles when it is activated even though the afr seems to stay mostly stable. I have changed ae settings to match another vehicle running well, so I will see if that works better. I also changed up my bins for both tables so I have better resolution at idle. Unfortunately i most likely won't be able to get back to the truck until sat

[hybrid]

So, to make the 351 cam work in a non HO 302 all you need to do is chance the firing order?
David

Correct, and if you're running wasted spark, then nothing needs to change.
Here are the firing orders:

289 1-5-4-2-6-3-7-8
302 (Pre-82) 1-5-4-2-6-3-7-8
5.0 1-5-4-2-6-3-7-8
5.0 HO 1-3-7-2-6-5-4-8
5.0 Truck 1-5-4-2-6-3-7-8
351 1-3-7-2-6-5-4-8

So you can see with the 5.0 and HO firing order, cylinders 5 and 3 are transposed, as are 4 and 7.
Cylinders 5,3 reach the top together as to 4,7 it's just that the strokes are transposed, so one is on compression and one is on exhaust.

If you're running a distributor, simply change the leads around to match the right firing order. If running wasted spark, no changes required.

[turbo conversion]

So, to make the 351 cam work in a non HO 302 all you need to do is chance the firing order?
David

Correct, and if you're running wasted spark, then nothing needs to change.
Here are the firing orders:

289 1-5-4-2-6-3-7-8
302 (Pre-82) 1-5-4-2-6-3-7-8
5.0 1-5-4-2-6-3-7-8
5.0 HO 1-3-7-2-6-5-4-8
5.0 Truck 1-5-4-2-6-3-7-8
351 1-3-7-2-6-5-4-8

So you can see with the 5.0 and HO firing order, cylinders 5 and 3 are transposed, as are 4 and 7.
Cylinders 5,3 reach the top together as to 4,7 it's just that the strokes are transposed, so one is on compression and one is on exhaust.

If you're running a distributor, simply change the leads around to match the right firing order. If running wasted spark, no changes required.

Cool, love learning new stuff.

All my previous experience tuning has been GM and Chrysler with carbs.

My last two projects have been turbo Datsuns with MS2 Extra.

David

[Tjohnson]

alright, so i was able to make it out to my shop after work today, since i fixed the blend door in my car and i actually have heat now. woo

i checked over the engine bay, topped up the rad, checked the oil, and then noticed the vacuum port on the brake booster was unplugged, so that probably why i had such small vacuum.
anyways, i added some timing at idle, which helped a bit, and i changed some tps ae settings, and that seemed to help quite a bit, but now when i slowly roll on throttle, it leans out and then finally clears up and revs. but when i stomp the throttle, it revs right up.

I really dont know what to do when it comes to map or tps based enrichment, could you help me out?

thanks

[turbo conversion]

Your problem is not AE, it is your afr and ve tables they are way to lean.

With your cam and being non sequential 14.7 afr is to lean, try setting the afr to 13.5.

You can use the throttle to hold the rpm steady then add fuel until the engine is happy.

Don't get hung up on afr numbers and what you think they should be, make the engine happy.

David