Car runs like crap under load. Need Ideas

moneypit94 · Apr 5, 2005

Recently my car started running like crap under a load. It seems to idle just fine and under most circumstances it runs like usual.

But if i try to push it it kinda acts like its missing. And when i try to rev it up it is sluggish and will crackle and backfire.

Anyways here are the things i have tryed... I unhooked the msd box, and it ran the same. I tryed a new coil, new wires, plugs, cap, and rotor. Nothing. I unplugged the spot wire and it died like it usually does with out a little extra fuel.

Now here are the next things i think im gonna try. Going to check the resistance in all the injectors and see if they all are the same. I may try a new ignition module.

Im kinda running out of ideas here. My PMS shows that im getting boost but i can't feel it. My fuel pressure is at 40 like normal. I haven't really checked it under a load, but i can't even rev my motor up without problems.

Any Ideas or tests i could do? Like a said im thinking maybe bad injector and the only thing i can think of is to see if they all read around the same.

95snoozer · Apr 5, 2005

02 sensors

almost certain

i hope you didnt run any leaded fuel or heavy race gas did you?

moneypit94 · Apr 5, 2005

I did last race season, but haven't this year... That had slipped my mind though.
My PMS shows readings on them, would that be noticable.

Also that brings up another question. Isn't there a way to make it to were they read whatever you want them to read. Like aftermarket 02's so you could run race fuel?

Zero Signal · Apr 5, 2005

Seems like a fuel pressure regulator or pump problem. Possibly vacuum? Just gotta start eliminating things starting with the easiest/cheapest tests

94TURBO5 O · Apr 5, 2005

Are you running the O4 P.M.S version?

If you are what are your load tables set at from LL- H?
Are you running Idle control?
What are your fuel tables set @ in WOT & BOOST?
Do you have Stand Alone ON?
If you got time give me your tune. What cells you have programmed.

95snoozer · Apr 5, 2005

moneypit94 said:
I did last race season, but haven't this year... That had slipped my mind though.
My PMS shows readings on them, would that be noticable.

Also that brings up another question. Isn't there a way to make it to were they read whatever you want them to read. Like aftermarket 02's so you could run race fuel?

with a pms i thought you could tune it as a standalone and possibly lock them out

91LX_5L · Apr 5, 2005

check plugs/wires mine did that and it was the cause

yellow1995Cobra · Apr 5, 2005

Does it do this while the engine is still fairly cold?

While its warmed up?

What dist you have in there?

moneypit94 · Apr 6, 2005

yellow1995Cobra said:
Does it do this while the engine is still fairly cold?

While its warmed up?

What dist you have in there?

Does the same weather it is cold or hot. Have the stock distributor in. Its only got like 10k miles on it though. Plus from my reading the only difference between it and a msd distributor is the shaft and maybe the bearings. And i have checked them out and they seem good.

91LX_5L said:
check plugs/wires mine did that and it was the cause

I have replaced both in attempt to fix the problem and no luck. I am going to try o2's today.

94SC50:
I am running the 04... I am planning on having the car retuned at AFM later this spring. i don't know if you would want my tune intill then. car runs a little rich in places which is safe but bad on plugs. (this is not the cause of the problem at hand though)

moneypit94 · Apr 6, 2005

95snoozer said:
with a pms i thought you could tune it as a standalone and possibly lock them out

To tell you the truth im not sure about the standalone. i think it kicks on around 3000+ rpms... I will have to check that out later today and see if its even enabled.

moneypit94 · Apr 6, 2005

Today i tryed a new 02 sensor. Only got one because thats all autozone had. I tryed it on both sides and got pretty much the same readings and same problem.. I also reved up the motor and the fuel pressure climbs a little like its supposed too... I even checked the fuel for water..

On my PMS it shows no errors.. So im kinda lost right now.. I even checked the MAF to see if there was anything on the sensor, nothing...

Im thinking of checking the valves to see if maybe one tightened up somehow? The only other thing is maybe a ignition module?

I also need to check the timing to make sure i don't have a timing chain or somethign wearing out...

Is there anything im missing

BTW... I HAVE A new (only been used for 10 or so mins.) 02 sensor if anybody is interested let me know.. will shoot you a deal.

nmcgrawj · Apr 6, 2005

Thats how my car was before i added the aftermarket ignition with the PMS...but i saw you said you had one so i have no idea. But those are the symptoms when you run a stock ignition and a PMS on a 94-95.

Are those the symptoms of a bad ignition module? I hate for you to keep throwing money blindly at this thing....unless you got it like that

mo_dingo · Apr 6, 2005

Remember, at WOT, the O2 are ignored. So if the same problems occur when the car has been running for a while at part throttle & when you are WOT, the O2's are not your problem.

Start with the simple things. Don't just go replacing thing arbitrarily, you will really want to call your car a moneypit.

Can you datalog with the PMS?

Start with the simple stuff, check fuel pressure, check vacuum, check spark plugs/wire/cap/rotor, clean your MAF/IAT sensor, etc.

If you can datalog, see what values you are getting at your IAt sensor and your ECT sensor and convert them into temperature numbers, and see if they are right.

next datalog your MAF values and convert to kg/hr and see if they are in the ball park.

My guess is it's an ignition issue, not a sensor issue. When you are running on the O2's, it should eliminate any problems you have at cold start/WOT runs.
Scott

Tayohs 95Gt · Apr 6, 2005

holy shiiiiiiit im havin the same problem but it iwll run fine sometimes, then it will miss really bad and it seems like its not runnin on all cylinders.. i dunno i was kinda thinkin the o2 sensors but im not sure

RIO5.0 · Apr 6, 2005

Performing a vacuum test is real simple and a gage set-up at AZ or the like will cost likeunder 15.00...

Plug it in and youll see instant results at idle if its pulling a decent number...bring up the RPMs and watch the needle...It'll tell you if your leaking, or if you suspect the valves you see it right off on the gage...nice little tool to have around...

moneypit94 · Apr 6, 2005

RIO5.0 said:
Performing a vacuum test is real simple and a gage set-up at AZ or the like will cost likeunder 15.00...

Plug it in and youll see instant results at idle if its pulling a decent number...bring up the RPMs and watch the needle...It'll tell you if your leaking, or if you suspect the valves you see it right off on the gage...nice little tool to have around...

My pms has a 3 bar map sensor hooked up so it gives manifold pressure... I have have good vacuum...

Im gonna start looking at all the basics again... Got a few new ideas from you guys...

Car runs like crap under load. Need Ideas

moneypit94

Active Member

95snoozer

Active Member

moneypit94

Active Member

Zero Signal

Active Member

94TURBO5 O

New Member

95snoozer

Active Member

91LX_5L

yellow1995Cobra

New Member

moneypit94

Active Member

moneypit94

Active Member

moneypit94

Active Member

nmcgrawj

Advanced Member

mo_dingo

Tayohs 95Gt

New Member

RIO5.0

moneypit94

Active Member

Similar threads

Car runs like crap under load. Need Ideas

Active Member

Active Member

Active Member

Active Member

New Member

Active Member

New Member

Active Member

Active Member

Active Member

Advanced Member

New Member

Active Member

Similar threads

Privacy & Transparency

Privacy & Transparency