Knocking under boost

[glhs399]

I'm having issues with the 87 Horizon that I just bought. It is knocking under boost. The car has been sitting for just under two years. It has had a 85 T1 2.2 swap and a MP computer, 2.5 exhaust and other than that it appears to be stock.

The symptoms are:
Knocking under boost
hard starting (starts better when you give it a little gas)
dies when you rev it up and let it back down to idle. It has a hard time finding idle after revving it up and most of the time dies. If you help it with a little gas it will settle down and idle on it's own.
The car is smoking a little bit after you let it idle for a few minutes so I'm thinking it's just valve guides.

Codes: 12 (Battery feed to computer) and 41 (Alternator Field)


Here's what I've checked and changed so far.

I drained and added new gas (Helped some)
Checked cam timing and distributor timing. Reset distributor to 12 degrees was set to around 15 (Helped a little)
Checked for vacuum leaks
Checked fuel pressure: Static 30 pounds then bleeds down to zero (It usually doesn't bleed off pressure right away does it?) Running 49 pounds
Compression test: 120 115 110 120 (seems low to me)


Any other ideas on what to check and test are much appreciated! I have a OTC 4000 but I just started playing around with it. I would like to race this at the Bible Creek hill climb next weekend. Back to the garage to see what else I can figure out.

Picture of the plugs I pulled out:


The distributor seems way off to me:

[turbovanman²]

Number one, throw those plugs away, they are probably your problem. I would redo cam timing from scratch. Fuel pressure is also low, it should be 55 with the + terminal on the coil to battery power.

[black86glhs]

Number one, throw those plugs away, they are probably your problem. I would redo cam timing from scratch. Fuel pressure is also low, it should be 55 with the + terminal on the coil to battery power.

+1000 on all points. Platinums are a nono in these cars.

[glhs399]

Plugs are already in the garbage. Replaced with NGK, I like the AR 51 but I had some NGK's laying around. I'm going to try and replace the fuel filter and see if I get any better pressure. If not I'll throw in a new pump. Keep the ideas rolling in! Thanks guys.

[bakes]

redo you timing belt / cam and I shaft timing, they are most like off.

[jl93sundance]

distributor looks to be waaay off, would check timing like others have said, first ignition timing then go from there.

[chilort]

I have some of these symptoms too. It is hard to start, has died after revving it, and the fuel pressure drops like a rock when turned off. My timing is dead on and I've set it, reset it, and verified it more than a few times.

[glhs399]

Redid the timing and still no change. 99% it's the fuel pump. Took the hood off and taped the fpg to the throttle body and fuel pressure is steadily dropping off when it gets to boost. I tried to get a new 190 locally but no luck. I just ended up paying for quick shipping from FWDP. I want to do a hill climb in the car and that this Sunday. Hopefully that cures all the issues. I'll update the thread when issue is resolved.

Chilort, be sure to do all the fuel pump tests that turbovanman has posted in the knowledge center. http://www.turbo-mopar.com/forums/vb...e&articleid=36

[turbovanman²]

Glad you think you found it,

[chilort]

My FPR is an acufab and is only a year old or so. The injectors are Mopar 804s and are about a year and a half old. The fuel filter is maybe 2 years old. The way mine acts, I think it might be the check valve in the fuel pump. My acufab does not leak out of the vacuum port (I've double checked) and handles pressure well. If I pinch the line the fuel pressure goes up. I have not done the test to confirm the check valve yet though. I'll need to check that out when the wife gets home since the pressure drops so fast I'll need two people. BTW: Simon, that is a good KC article. I didn't know it was even there though.

What kinds of drivability issues might I see with the check valve messed up?

[fastasleep]

Chilort, I have an extra (new) 255 in-tank if you need to check it out to see if yours is bad. I am in the Atlanta area (Covington, east of Atlanta on I-20). Let me know if I can help!

-Les
770-778-7368

[chilort]

Les

As soon as I get the radiator fans and ac running again I'll check this out all the way. Long story short, it was a long day getting to work today and I'm glad I keep some spare wire in my hatch.

Jeremy

[fastasleep]

I am here if you need me, man. I have quite a few spares and such, so if you need some parts in a pinch I'd be happy to help out. Like I said, I am local, so you could possibly have parts in no time. Do you have the fan and a/c parts you need?

-Les

[glhs399]

New pump cured my problem. A big thanks to FWDP for getting me one in two days! No knocking anymore and it's pulling quite nice. I forgot what it's like to drive a T1 Omni. Hill climb for me on Sunday

[bakes]

New pump cured my problem. A big thanks to FWDP for getting me one in two days! No knocking anymore and it's pulling quite nice. I forgot what it's like to drive a T1 Omni. Hill climb for me on Sunday

Well how did you make out?

[glhs399]

Didn't make it to the hill climb, I went to hook up the tow dolly to the van and I couldn't find my ball mount for it. I specifically put it in the wooden tote that has all the other tow dolly supply's in it but no where to be found! The last one to borrow it was my buddy was already there and he was already at the event camping and had no cell service. I called around to a few people that I knew that had some but none of them had enough lift. By that time it was 12:00 am and I was pissed off. I didn't trust the car that I bought a week ago and got running Friday night to make it there (Around 80 miles.)Then go beat on it up a hill and then drive back. I just stayed at home and worked on other car projects. Oh well, I'll go next year and I think I'll catch the next close autoX. It ends up that my ball mount was sitting in front of his truck!