1994 454 TBI runs rough, misfires, backfires, dark exhaust

[CJ7365]

Kenny,
I would be interested in which OBD I monitoring systems you bought, I might be interested in this.

I was not sure you could monitor OBD I system, I have vehicles that run OBD II and really like that I can monitor a lot of variables.

[kennyrodgers]

Hi CJ,
I havn't bought it yet but I've been in touch with the guy who makes the scanner and the app to go with it. He assures me it'll work fine with my RV so I'll be ordering one this week. I already have an android tablet so it'll work out cheaper than buying an OBD1 scanner. BTW, the app is $19 give or take.  I can see a double benefit with this as it's real time so as far as far as I can tell you could use this for going down the road with the tablet somewhere on the dash.
There's links to the company I spoke to in the video.
http://www.youtube.com/watch?v=fibnQ7axKB4

[kennyrodgers]

Apologies, I didn't see the replies from Motor Pro and the other from Rick about the propane.


Part of the problem being in the UK is the availability of parts. I've managed to get some stuff from the UK, things like rotors, caps, leads etc are readily available but try to find a TBI rebuild kit or injectors and nada.
I've also found a local injection specialist who's confident he can service my injectors but hasn't got o-rings or filters.
I weighed it all up and decided that there's not much point in ordering a couple of things from the USA and it not fixing the problem then having to wait another fortnight for other bits to come. The other thing to consider is that my engine hasn't run on gasoline since 2007 at the latest. For the sake of it I thought I'll get everything I've got and be done with it. If it doesn't need it now at least I have it if a part fails.
My plan is to get the TBI rebuilt with new gaskets etc, fit the new injectors, CTS and o2 sensor and take it from there. The cap, leads,rotor and plugs were already on the to do list.
Propane is very easy to get over here, currently it's around half the price of gasoline @ £.46 per ltr for LPG and £1.12 per ltr for decent unleaded. Three places within a 2 mile radius of home and enough places dotted throughout the country that should make journey planning not too big of a headache.

[Rickf1985]

What I am saying though is from what I have heard you will burn through your propane tank in about 250 miles. Or do you have a second propane tank just for motor fuel. The people I talked to the propane came from their regular coach tank. Propane filling stations over here are not that easy to find since it is not generally used as a motor fuel here. Some truck companies use it but they are generally local haul companies so they have their own fill tanks on site and fill up at the beginning of every day. I know of no on road filling stations. anyone else here in the USA know of any? I am stuck on the East Coast so things may be different going west. Haven't been out there in many years.

[CJ7365]

Hi CJ,
I havn't bought it yet but I've been in touch with the guy who makes the scanner and the app to go with it. He assures me it'll work fine with my RV so I'll be ordering one this week. I already have an android tablet so it'll work out cheaper than buying an OBD1 scanner. BTW, the app is $19 give or take.  I can see a double benefit with this as it's real time so as far as far as I can tell you could use this for going down the road with the tablet somewhere on the dash.
There's links to the company I spoke to in the video.
http://www.youtube.com/watch?v=fibnQ7axKB4

Thanks Kenny

That is very interesting, thanks for posting the link

[kennyrodgers]

Hi Rick,
My system uses a separate 200 ltr tank that's just for the engine. I'm confident that pretty much all dual fuel converted RV's over here do as well. Twin 100 ltr or single 200 ltr are the norm and It's totally independent from the system in the coach. I'm planning to see what sort of range I get and then if needs be there's plenty of places to fit a second.
Gasoline prices over here are probably the reason why it's so readily available although if the media are to be believed it's use is on the decline.

[legomybago]

What I am saying though is from what I have heard you will burn through your propane tank in about 250 miles. Or do you have a second propane tank just for motor fuel. The people I talked to the propane came from their regular coach tank. Propane filling stations over here are not that easy to find since it is not generally used as a motor fuel here. Some truck companies use it but they are generally local haul companies so they have their own fill tanks on site and fill up at the beginning of every day. I know of no on road filling stations. anyone else here in the USA know of any? I am stuck on the East Coast so things may be different going west. Haven't been out there in many years.
[/quote
You can get your propane tanks filled at thousands of gas stations over here it the west. The West is the best, the East is the least. 

[kennyrodgers]

Little bit of an update....
Busy at work so havn't managed to get stuck in yet however.....I had an hour today so nipped down to change the ECT and MAP sensors. Low and behold....the vacuum pipe was off from the MAP sensor. Talk about not seeing the wood for the trees. I fitted the new one anyway, hooked up the pipe and a massive improvement....as you would expect.  Most of the vacuum pipes have hardened and are quite brittle so I'll change all of those out as well.
She's still not quite there yet but work starts in earnest this coming weekend.

[Rickf1985]

It will run better as the ECM relearns the fuel strategy. It takes a few hours of normal driving to relearn.

[kennyrodgers]

Cheers Rick,
I didn't realise it did that and good to know.
Once the work's done I'm planning on taking her for a good two hour shakedown run, check everything over then build on it.

[kennyrodgers]

It's official.......
It's official.....
My injectors are lost in the post. Thank you USPS and Parcel Force UK, great job !

[Rickf1985]

Most likely the USPS side of it. Hm? i??   How long before you can file a claim and get replacements?

[kennyrodgers]

Well waddya know, they're here lol. Just got in from work and they're sat on the table.
They must not have been scanned at all once they arrived in the UK.....Fills you full of confidence eh !!
Turns out USPS did OK on this one after all Rick.

[kennyrodgers]

Making progress now....
Got most everything done bar rebuilding the Throttle Body with the new injectors. We've sorted out the backfire as well.....this is where I hang my head in shame....I'd got plugs 3 and 5 arse about face as we say over here. She's running pretty sweet now if a little rich still.
One thing that's got me stumped though, well two things actually. I changed the ECT at the front of the engine but there's two similar looking sensors, one on each cylinder head in the middle between the two inner most cylinders.
Any ideas folks ??
Thanks in advance,
Pete.

[DaveVA78Chieftain]

Look through these L19 (454) drawings to see if you can ID what your looking for
http://www.gmpartseast.com/Page_Product/PartsComponent.aspx?MakeUrl=chevy&CatalogUrl=1994-p30&SectionUrl=engine&EngineCode=L19&TransmissionCode=M40

[kennyrodgers]

Many thanks.
Looks to be another type of coolant sensor then. I can't find the one that goes into the front of the block though.
Hey ho.

[Rickf1985]

The one on the thermostat housing usually goes to the gauge and the one on the side of the engine goes to the computer. Now, there is also a knock sensor on the side of the engine with a similar connector. Should be above and in front of the starter. The coolant sensor on the side of the engine, or one of them could be a coolant fan switch.

[kennyrodgers]

Another update and another issue....
We got the TBI rebuilt with the new injectors, happy days. The engine is running great but now we have a high idle issue. We didn't go near the IAC with any type of carb cleaner at all but she was idling nice and low before the rebuild......
Any pointers would be appreciated.
In other news......the water pump is also toast, new one arriving tomorrow. We managed to get everything out the way bar for one bolt in the steering pump mounting from the doghouse. I'm venturing underneath tomorrow to see what we can see.
Two steps forward one back once again.

[SLEETH]

hi, the high idle is some time caused by a  battery  being disconnected(long period) & or iac being disconnected & ign turned on (bad) = the ecm needs to do a relearn= need to drive=to relearn(if lucky)

[Rickf1985]

Are you sure you do not have a vacuum leak from the injector operation? That would be my first thought. Vacuum line left off? If not then disconnect battery, turn headlights on (they will not come on but will drain keep alive memory) for about ten minutes and then turn lights off and reconnect battery and try again. If still idling high check for vacuum leaks with carb spray around all areas you were working. Be sure air cleaner is on good and sealed or you will get a false signal. Check to see that mechanical linkage is not binding and or out of adjustment also.

[kennyrodgers]

Thanks for the replies gents.
I'm pretty sure the key hasn't been turned whilst the TBI's been off the engine but......not sure if it's relevant or not....I removed the TBI when the engine was cooling down after it had been running (in park) for a while whilst we had been checking the timing, new plugs / leads etc.
Also re the battery, she's been sat for a week with the engine and coach batteries isolated via with the master switches. I tend to do that after every visit.
We're confident there's no vac lines missing or leaking, I learnt that lesson after the MAP line was off. She runs really rough with even the smallest of lines off but apart from the high idle, she's running sweet.
Not checked the bottom gasket with propane but it was in very good shape.

[SLEETH]

if you where in the neighbor hood I would loan u my iac controller & noide light = that way u could command the iac in all the way=and if u still had a high idle= then u got a vacuum leak
do u have access to a scanner=read the o2 sensor =will confirm if u have a vacuum leak as well
did any one play  the base idle screw on the side?

[Rickf1985]

Always go back to the last thing you did. as long as you did not move the base idle screw then you probably have a leak at the gasket. Did you use any sealer or did you just put it back on? If you did not use any sealer I can just about guarantee you have a leak.

Here is another possibility, the PO may have turned the base idle adjustment up to compensate for the bad injectors that were in there before. Is the plug over the base idle setting screw still in place or has it been removed? If it has been removed then it is probably a good idea to seal the gasket under the throttle body and then do a base idle reset. That way you know you are starting from square one.

Here is a link that explains it as well as any.

http://www.ehow.com/how_7959677_reset-baseline-idle-gm-tbi.html

[kennyrodgers]

Hi Rick,
My buddy refitted the TBI whilst I was on other duties but I'm pretty sure he didn't use sealer. Re the PO, yeah, it's certainly a possibility so I'll check that out.
I have some Aircraft quality RTV somewhere, would you coat both sides of the gasket or just the face side of the intake manifold ??


Some more advice re the water pump as well if I can.
I got the replacement today and it's a Cardone 55-11111 standard duty. I'm in two minds whether to send it back or not as Cardone list an "H" version that's listed as "Extra Duty"......
Do I order that one from Rock Auto and wait two weeks to get it or is the Std duty up to the task.
Thanks again guys, I'd be in a bit of a pickle without ya.
Pete.


PS, thanks for the link re the idle adjust.

[cncsparky]

New gasket with no sealant on carb/tbi base to manifold.