I had a scan done on my friends car that we have a popping problem with.
If possible can anyone point me in the direction to look at into fixxing this problem?
Results are as follows.
engine Off\eng running open loop\engine closed loop\snap to 3670rpm
tpsvlts .56 .56 .88 2.50
blkLrn 128 150 136 136
plswth .0 3.0 2.7 7.0
idlerpm 3188 800 800 800
MAF 23gm 11gps 32 149
airflw 61gps 11gps 32 153
Vats yes
RPM 0 760 2150 3670
O2 0 130/280 852 102
exhaust reads lean lean lean
airflw lrned none yes no
coolant °'s 161° 170° 185°
MAT°'s 82° 82° 86°
Load 0 76 72 186
spk adv 0 26° 38° 30°
intgrte 0 0 130 128

When you roll on the throttle hard the motor lean pops out the intake under 2200 rpm.
Car will run up to 6000 easily
This is 383,brodix head,10/1 comp ratio,cam 232@.050
Tpis Mini ram long tube headers,plugs are black rich reading
cam was degreed
Just tried a different MAF and the car will barely idle and shuts off when given throttle.
thank you

 

The MAF, LV8, spark advance, RPM, and integrator numbers look like they shoudl . P/W looks O.K. Basically, nothing is glaring except the lean indication.

What is fuel pressure? Are you sure the ignition system is intact, and you're not getting spark scatter? Are you using a new O² sensor? The black plugfs don't agree with the O² counts and BLMs.

 

fuel pressure can go to 50 it doesn't make any differance.
Looking at the graph the MAF is reading airflow when the engine is off???
Is this correct?
The ignition is in good shape,when you roll on the throttle the o2 is going to 102.
The car ran fine before the engine rebuild.
We swapped to another MAF and the engine doesn't want to run at all.

 

ttt

 

I need to scan my MAF to see if that is correct.

When you say the O2 is going to 102, do you mean it's leaning out that much? As in 102mV?

Is it just pop when you roll of the throttle, at idle, or all the time?

 

I'm told the O2 isn't getting hot enuf at idle,should be around 850/900mv is this correct?

If so this would cause a lean condition as read by the O2 sensor in MV's and black plugs caused by the extra fuel from the computer compensating.

The pop is rolling the throttle on in gear and in neutral under 2200
after that it runs like a scalded dog.

 

Don't ask me to explain it, because my brain isn't working right now. It is the opposite, 850-900mV means that you are running rich, almost as rich as the O2 can read (O2 maxes out at 1.1V).

Black on the plugs means that you are running too rich, this would complement my first answer.

The pop would mean that you have to much fuel running into the headers/manifolds and probably detonating in the exhaust. As for running well in the upper RPMs, these cars run fine when rich that high.

Are you running any after market products for the fuel, such as an AFPR or anything? Second is this a stock chip or is this an aftermarket?

 

idle mv's are 130/280 means its not hot enuf?
ecm see's this as lean verified by lean signal in the exhaust so it adds fuel giving me black plugs.
What do your O2's read at idle?
what does you maf read with the key on and engine off?
Thanks

 

mV will not be able to tell you if the O2 is not hot enough, but it can tell you if something is wrong. There are other problems that could keep your O2 sensor voltage that low. A faulty O2 or not heated enough.

If the O2 sensors cross counts are not elevating quickly enough would be a good 'pointer' at the O2 sensor. This will either mean that the O2 is faulty or not getting hot enough, if it is elevating quickly, then it probably means that you have a bad ground, or loose connection.

I don't remember what my MAF says at idle, I haven't had a chance to scan my car yet, that and I don't have the program at the office.

 

thank Maroon,
O2 counts are very active the sensor is a new 3 wire.

The pop is out the intake (lean pop) ignition timing is correct.

 

MAF reading is 23 grams with the key on and engine off.
Will this be considered functioning normally?

 

Might want to post this on DIT prom tuning board!

Sounds like a chip tuning problem to me!--possibly in the timing table--but I don't know enough about the subject to advise properly!

Know any good chip tuners in your area?

 

please keep us posted on how this turns out, my new engine is doing the exact same thing? i have went through everything i can think of.

 

In rereading the post, the blackplugs, the O2 info, it (IMO) sounds like it is way rich--it may be good at wot, but old school has always taught me that when U open the throttle, and it's popping, it's way rich. If it were a non-computer--carb car, I would be backing off the pump shot, until the pop goes away--providing everything else is right--again if it were a card N/C I would be looking at timing advance rate--probably changing advance springs.

I can tune the crap out of old style cars--raced drag--roundy round seveal years--head wrench on a local sprint car for couple years (won the points championship one year with 7 feature wins), but I am at a loss at being able to work with rewriting chip and chip tuning in general.

Does this car have a chip tuned for the new motor configuration? What chip is/was in there before all the mods were made?

When did the popping start?

 

Zap,
When you roll on the throttle hard the motor lean pops out the intake under 2200 rpm.
Car will run up to 6000 easily once its over 2200 rpm.

Lean pops out the intake due to the almost instant airflow and no fuel to cover the hole in the fuel curve it creates.
Fat pops out the exhaust and usually will roll a black smoke cloud although the plugs read rich the the sensor tells the ecm lean and to add fuel or so I'm told.

I'm with you though if it was a carb this wouldn't be happening!

 

Well, I know all situatuons are different, but my tuning experiances do not necessarly agree with that.

Just last week we did some chip tuning on my car (see mods below) --one of the things i had was pretty much the same condition--its gone now--did it by backing the fuel and using a different timing table on the low end with pretty much the same numbers and mid range and top end.

Don't ignore the black plugs! Your engine is trying to talk to U (if U will)--its trying to give u info. Unless its oil, black plugs only mean one thing and one thing ONLY!!!