Author Topic: 318 TBI unstable idle and lag when accelerating  (Read 6294 times)

0 Members and 1 Guest are viewing this topic.

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
318 TBI unstable idle and lag when accelerating
« on: July 28, 2012, 09:38:27 AM »
Hi
I Don't have Ramcharger but decided to post here because I know you guys are knowledgeable about TBI
I bought Dodge b250 few months ago, it's 1989 TBI 318 and I'm spending a lot of time trying to solve his puzzle.
my 318 have big problem with Idle RPM and throttle response.
Idle goes up and down about 100RPM, it happen suddenly and quite often.
Other thing is that it have huge lag/bog when I hit the accelerator pedal(under load engine dies) and backfires ( without doghouse and air filter it could burn eyebrows and scare to death...) everytime engine come back to idle it goes a bit too low, 400-600 RPM before ISC react.
What I did :
- Disconnected ISC --> No difference, so ISC is just doing corrections and it works.
- Cutted exhaust pipes after manifolds(before it had single pipe with lame catalytic converter) --> and it helped, engine is not dying anymore, can't see any backfire and it sounds great!   still have other problems
- Different ignition advance setup --> No difference
- Changed spark plugs(gap checked), and all of them are getting good spark
- Throttle body disassembled and cleaned several times and it wasn't as dirty as I was expecting, new gaskets, --> No difference
- Cleaned all vacuum hoses and solenoids, sealed vacuum tree --> No difference
- No fault codes after keydance (12 55)
- New fuel filter
- Cleaned computer, connectors, checked for good ground
- New engine oil and filter
- Have been running with injector cleaner in fuel
- Checked fuel pressure, it stays strong at 14,5 psi even at road test when i was forcing it to stall
- Checked other mapsensors(including GM) and their voltage --> No difference, at least not I was looking for
- Injectors have 1.8 Ohm resistance
- TPS checked voltage, don't remember what it was but was changing in proper range
- Tried to look at injectors spray pattern, it's cone shaped but I don't have enough experience and good strobe light to determine what i see is good or bad, I'm also not experienced in searching for vacuum leaks.
- EGR I think is not working, it have completely rotten cap(I can put finger inside it), plugged vacuum hoses, tried to remove it but these bolts are welded !!

Already removed Air pump, cat, air conditioning, changed fan to electric.
It's not a daily driver or work horse and I want to wake up this motor in closer future so I consider carb conversion.
My last mileage was 10mpg with 70% city driving and cast iron right foot, I don't know what numbers should do TBI in good condition.

I had before 2 cars which were EFI and my experience is that it's much easier to get used to the problem, drive it and sell your fuel injected problem to someone other (it doesn't mean that did nothing to solve it).

I'm asking all of you for help because I'm running out of ideas.
Thanks

Offline RCCDrew

  • Jr. Member
  • ***
  • Posts: 803
  • Your only limitation is your attitude.
318 TBI unstable idle and lag when accelerating
« Reply #1 on: July 28, 2012, 10:10:44 AM »
You've covered a lot of bases. Good work. Sure there is no exhaust gas getting back through the intake?  That still wouldn't explain the idle surge. Does the timing stay steady, timing chain tight?
The "experts" are great at telling you what you can't do. Don't let someone else's opinion be your limiting factor.

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #2 on: July 28, 2012, 10:32:31 AM »
Which wire did you unplug to set timing? If none, then timing is all screwed up. Since you dont have a timing light to use strobe on injectors its safe to assume timing wasn't set with a light either.

Otherwise you will likely find a compression problem in your valve train....

Offline DODGEBOYS

  • DODGEBOYS.NET / RCC Signiture Police
  • RCC Addict
  • ********
  • Posts: 22174
  • Gender: Male
  • show me the Flame and l might see the light
    • DODGE TRUCKS @ DODGEBOYS.NET
Re: 318 TBI unstable idle and lag when accelerating
« Reply #3 on: July 28, 2012, 11:59:23 AM »
most 1988 to 1991 TBI problems [1989 is the worst] can be traced to a wiring problem / and its the connectors at the back of the right valve cover / the picture below is extravitgated to show detail


(Sorry, but you are not allowed to access the gallery)
put your truck info HERE
MOPAR TO YA! AARON HOWORD TOWNSEND / SLANTEDMIND---GOD BLESSDODGEBOYS FSM STORE
ramchargercentral@hotmail.com
DO NOT use the site IM,s to contact me  l have them turned OFF

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #4 on: July 29, 2012, 09:36:57 AM »
I cleaned those connectors too, that was the first advice I found when i was searching this forum.

well I didn't tried to set timing professionally, just checked what happens when i set it in other position, and after came back to original setup.  I don't know in what shape is timing chain, I haven't changed water pump

EGR and its hoses has been messed by previous owners
Today I checked EGR pipes going from exhaust manifolds and they looked like may cause serious leak, so I plugged them and pipe to airpump, engine was running still the same but I noticed that it is sucking air from pipe which was connecting egr valve and airpump.
I'm still confused but at least I know I have to get rid off that valve. I wanted to mount blockoff plate there before but gave up when i saw these bolts.
I'm buying better intake manifold and in the meantime I'll be trying to do something with egr valve

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #5 on: July 29, 2012, 03:24:02 PM »
I hate to say this, because you have been so thorough, but you and i both know that compression, vacuum, and timing test (all with proper numerical tools) is necessary. Whether you choose to follow through, is completely up to you.

Not all poor running engines are electronic related.

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #6 on: July 29, 2012, 04:46:58 PM »
I don't have workshop full of finest tools but I'm just in the beginning of my collection. I try to check as many things as possible in easiest way. And you are right, I should plug in vacuum gauge, check compression and set ignition by using good strobe light and disconnecting temp sensor.
I tinker with EGR right now and I'll let you know about effects later

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #7 on: July 29, 2012, 04:55:48 PM »
No one says they all have to be new or extra expensive. The items mentioned used to be normal do it yourself tools. Think of the time spent already. That cost money. Some of these items are free loaners. Many are dirt cheap at auction swap meet or classifieds.

If you are going to mess with the egr, see if you can safely get some heat to it. Probably cant. If not, run it hot and soak it with kroil. You will have to buy the kroil online. Pb blaster or wd40 will just leave you frustrated.

Offline greenpigs

  • Newbie
  • *
  • Posts: 69
  • Gender: Male
Re: 318 TBI unstable idle and lag when accelerating
« Reply #8 on: July 29, 2012, 07:30:56 PM »
OP

I have a similar issue to yours but when I went to check the timing my light was weak and I didn't see the mark anywhere. Now I have a problem of is it the weak light or is the timing off to the point the mark is not visible.

Like stated you need to verify the timinig is correct by a timing light, not best vacuum like on an old school motor.

Does it start easy?
1989 Ram Charger 318 4 X 4 stock
1969 Charger RT

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #9 on: July 29, 2012, 07:45:16 PM »
OP

I have a similar issue to yours but when I went to check the timing my light was weak and I didn't see the mark anywhere. Now I have a problem of is it the weak light or is the timing off to the point the mark is not visible.

Like stated you need to verify the timing is correct by a timing light, not best vacuum like on an old school motor.

Does it start easy?

You unplugged a sensor to check it? If you just hook up light without putting engine in limp home mode, timing will be all over the place.

Offline greenpigs

  • Newbie
  • *
  • Posts: 69
  • Gender: Male
Re: 318 TBI unstable idle and lag when accelerating
« Reply #10 on: July 29, 2012, 07:50:00 PM »
Yes

The temp & the throttle one...I guess I should have stated that.

1989 Ram Charger 318 4 X 4 stock
1969 Charger RT

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #11 on: July 29, 2012, 08:00:52 PM »
If the bulb is dim, that is squarely the fault of the timing light or battery. The light is not supposed to vary brightness based on any engine factors.

On the other hand, it does help to clean balancer and pointer along with using a white paint marker on any lines or pointers or numbers.

If your balancer is real greasy and looks like front seal is or was leaking, and marks are no where near, you will probably have to replace the balancer. In that case, the outer ring has likely slipped from the rubber. Can even explode apart if separation is bad enough. Usually caused by oil damaging rubber, from a front seal leak. Crank speedisleeve may be required if grooved.

Offline greenpigs

  • Newbie
  • *
  • Posts: 69
  • Gender: Male
Re: 318 TBI unstable idle and lag when accelerating
« Reply #12 on: July 29, 2012, 08:20:02 PM »
I agree and it is a cheapo timing light so most likely the culprit.

The balance is clean but a bit rusty with no oil of any sorts, also with a white marked line & I cleaned the timing mark area before hand.

Time to get a better quality timing light and check again.

1989 Ram Charger 318 4 X 4 stock
1969 Charger RT

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #13 on: August 1, 2012, 03:19:41 PM »
Today I mounted blockoff plate instead of egr, I have done computer reset and road test.
there still is a problem, the only thing that changed is the idle at Drive/Reverse, now its rather 600 than 900 rpm like on Park/Neutral. It's my first car with automatic transmission so I don't know how it should behave.
In moment like this I'm thinking about carb swap.

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #14 on: August 1, 2012, 05:46:41 PM »
Still havent done simple tests and yet consider much more labor plus $750 in new parts that may not solve the problem? Im sure once that cost sets in along with knowing the fact it may not solve the problem, will help you see the error. If not, it can be an expensive lesson.

So far, there is no evidence of a fault in the fuel injection system specifically. Until you have proof of out of spec parts, refrain from any total system replacements.

Conversion to carb will also require a timing light to time replacement dustributor and vacuum gauge to tune carburetir. Miral of story? Whether you like it or not, the tools are needed.

Offline rjtx667

  • RCC Rookie
  • **
  • Posts: 355
  • Gender: Male
    • RamCharager.net - why not?
Re: 318 TBI unstable idle and lag when accelerating
« Reply #15 on: August 1, 2012, 09:41:49 PM »
Hows your O2 sensor?

My 91 TBI was not happy at all until I got the O2 sensor in good working order and in a good place. I had headers so I had to move it off the manifold.
1991 Ramcharger Canyon Sport 4x4 5.2l
1993 Ramcharger 4x4 5.2l - Trail Rig
2000  Mexico Ramcharger 5.2l
  408 Stroker
http://www.ramcharger.net

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #16 on: August 2, 2012, 08:42:04 AM »
I think computer relearned and now all is like before removing egr
I'm collecting tools right now.

The only code it flashes is about iSC because I disconnected it for a while, so O2 sensor seems to work, Am I wrong ? there also should be difference in running cold/warm engine because sensor need to heat up. when it's broken, computer takes his factory saved data to work(limp mode) and should throw fault code.
I can try to disconnect it and see what happen

I'm curious where exactly did you placed sensor, I'm looking for headers.

Offline DODGEBOYS

  • DODGEBOYS.NET / RCC Signiture Police
  • RCC Addict
  • ********
  • Posts: 22174
  • Gender: Male
  • show me the Flame and l might see the light
    • DODGE TRUCKS @ DODGEBOYS.NET
Re: 318 TBI unstable idle and lag when accelerating
« Reply #17 on: August 2, 2012, 10:18:51 AM »
l,d say you need a wiring pinout diagram of the PCM and verify with a multimeter the reading the sensors are putting out at the sensors and what the PCM receives
put your truck info HERE
MOPAR TO YA! AARON HOWORD TOWNSEND / SLANTEDMIND---GOD BLESSDODGEBOYS FSM STORE
ramchargercentral@hotmail.com
DO NOT use the site IM,s to contact me  l have them turned OFF

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #18 on: August 3, 2012, 04:04:42 PM »
lately I focused on injectors spray pattern, but this time I used strong light and found something interesting. They are spitting ! hard to see at idle, I kept him at stable mid rpm(about 3000) for more than few seconds and and I saw random spitting like a double dose of fuel.
I hope its the cause of my problem.
Its worth noting that injectors seemed to be in great shape when I pulled them and I also added STP injector cleaner to tank some time ago.
I'll take them to ultra sonic bath cleaning on Monday.

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #19 on: September 16, 2012, 01:45:26 PM »
Installed the new injectors and they still work the same way. I think computer is sending bad signal to injectors. In the meantime I bolted headers and edelbrock 2176 intake, carb will be next so I'm not gonna spend more money on TBI system.
Thank you for your help guys

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #20 on: September 16, 2012, 02:04:38 PM »
How are you going to fuel this carb? The stock pump will blow the carb internals "apart". Perhaps not actual destruction but the fliat needle ans seats wont hold it back.

Dont forget the kickdown cable.

And the voltage regulator.

And the electronic ignition.

You are looking at $1,000 by time its all said and done counting the price of headers. Aint even half way through the conversion yet.

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #21 on: September 16, 2012, 03:57:21 PM »
I already did research about that mod, including this forum
adjustable fuel pressure regulator 30-60$ in my country
refurbished carb 225$
carb calibration kit 40$
ready to run dizzy and coil kit 80$
still not sure about kickdown cable/rod but I can fabricate my own if I'll have to do it
I'm not from U.S so I appreciate any help

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #22 on: September 16, 2012, 04:20:15 PM »
Can you show a link for a bypass regulator under $50 from your region? Bypass tend to be more expensive than regular (dead head) and cost around $70 give or take.

The rest of your prices are inline with the US and on target for the previous mentioned price quote. (Counting intake and headers)

The voltage regulator is also not a big deal and the kick down parts are slightly more than $100.

Offline 340SHORTY

  • Sr. Member
  • *****
  • Posts: 4098
  • Gender: Male
  • on a steep hill
Re: 318 TBI unstable idle and lag when accelerating
« Reply #23 on: September 16, 2012, 04:48:26 PM »
What a can of worms. Time to go fishing.. 
Your truck info goes here...

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #24 on: September 16, 2012, 05:32:18 PM »
http://moto.allegro.pl/regulator-cisnienia-paliwa-uniwersalny-nowy-i2627121839.html
http://moto.allegro.pl/regulator-cisnienia-paliwa-uniwersalny-komplet-bar-i2622540370.html
http://moto.allegro.pl/regulator-cisnienia-paliwa-uniwersalny-nowy-i2609406719.html
http://moto.allegro.pl/regulator-cisnienia-paliwa-uniwersalny-silver-i2609954944.html
1PLN = 0.32 USD at the moment
I bought used intake for 100$, used headers were very hard to find so i bought new for 200$,
and it works, even with that small throttle body and that Amiga,Atari alike ecu

Captain Obvious I've got a feeling that you are trying to catch me on hypocrisy

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #25 on: September 16, 2012, 05:42:39 PM »
Nope, i just dont want you to skip something and damage more of your dodge or have stuff still not work.

Lotta people asking stuff like "how do make my fuel pump work?" Why wont my alternator charge ir why dont i have spark? Or why does my transmission slip.

Some go on to tell others they can do the job for "a couple of hundred" and were shocked to find the total estimate. I just put the info out there as complete as i can.

Other people may read this thread, then they will find out more about cost and things involved.

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #26 on: September 16, 2012, 07:13:11 PM »
ok, now I understand your point of view.
a lot of things can be messed when doing conversion, that's why I'm reading every thread, about that, i can find, to learn on someone else faults.
anyway I'll try to do it in the next spring/summer so I've got whole winter to prepare.
I haven't found any tutorial , maybe I should write one when I'll finish.
What in common have transmission slip and carb conversion ?

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #27 on: September 16, 2012, 07:23:05 PM »
People not figuring out how to hook trans throttle linkage up to carb. It is assumed that it "just makes downshifts" They leave it unhooked and say "i dont need that"

In reality, it increases hydraulic clamping power to the clutches as you apply more throttle. More clamping force means less slip. At the same time, it reduces clamping power during light throttle so the trans doesnt bang and slam during light shifts.



There are a lot of variations to the conversion, mostly simple differences in wiring. Favorite version involves keeping the relay and using oil pressure switch. No oil pressure=pump automatically stop (except automatic priming while cranking starter)

My least favorite way is what hacks do, they use crappy toggle switches not rated for electrical load of the pump.
« Last Edit: September 16, 2012, 07:26:58 PM by Captain Obvious »

Offline UltraTwist

  • Newbie
  • *
  • Posts: 12
  • RCC Rules!
Re: 318 TBI unstable idle and lag when accelerating
« Reply #28 on: September 16, 2012, 07:50:31 PM »
interesting, nothing happened when mine oil pressure sensor was unplugged

Offline Captain Obvious

  • Sr. Member
  • *****
  • Posts: 3553
  • Gender: Male
    • How to find truck help fast
Re: 318 TBI unstable idle and lag when accelerating
« Reply #29 on: September 16, 2012, 08:25:08 PM »
No no, i meant there is a way to rewire a idiot light oil switch (on/off only) so that it will turn pump on and off only when engine is running. This is a rewire modification for carburetors with electric fuel pumps.

It is a safety feature in the event your fuel lines are cut in an accident. Instead of continuing to spray fuel everywhere, it will automatically shut pump off.

Pump will also not continue running while the engine is off and key on.

Offline 340SHORTY

  • Sr. Member
  • *****
  • Posts: 4098
  • Gender: Male
  • on a steep hill
Re: 318 TBI unstable idle and lag when accelerating
« Reply #30 on: September 16, 2012, 08:26:32 PM »
you shuld write a tutorial on how to fix your ailing TBI system Instead of giving up on it and changing to a carb setup.. 

3 years ago I went through a ton of grief converting a 318 TBIpowered  truck to a 360 TBI powered truck. The 360 tbi that I bought had missmatched injectors, the Hall Effect sensor was erattic ect. I perservered and eventually figured everything out. I was about to give up and take the so called easy rount in doing a carb swap.  I was so happy when I finally got everything right. I would love to convert my 81 dually to TBI..
Your truck info goes here...