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Discussion Starter #1
Hello,

After going through a full engine swap (after diagnosing the issue here: http://www.landroversonly.com/forums/f40/head-gaskets-worse-45958/), we've got the new engine in. It'll start right up, and idle all day long, but if I hit the accelerator, it'll try to die. Pumping the accelerator will get the engine to rev up, no problem, but it's hard to get it to stay there.

Also, the problem with the old engine was cam being broken in three places.

Initially, the engine would start, but die immediately (2 seconds or so) -- we replaced the IAC with one off of the old engine, and it now idles fine. There is one code, and it's 1590 (ABS).

Changing the TPS position independent of the throttle plate makes no difference, and we're using a MAF that doesn't throw any codes.

Any ideas what would let it idle but not rev?
 

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Since this happened, have there been any other codes beside your 3 Amigo related 1590?
I would stat looking for a major vacuum leak and at the idle solenoid even though you have replaced it.
 

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Discussion Starter #3
Since this happened, have there been any other codes beside your 3 Amigo related 1590?
I would stat looking for a major vacuum leak and at the idle solenoid even though you have replaced it.
Mike,

There are no other codes -- it's just the 1590.

We also thought of vacuum leak. Might head after that. Would the IAC really affect non-idle situations?
 

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Discussion Starter #6
Bill,

We removed the cables from the bracket. During reinstallation, I hooked them up at a point just before they have pressure on them.
 

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Discussion Starter #8
Bill,

The throttle is hooked up to the one closest to the TB, the cruise to the furthest out.
 

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Discussion Starter #11
either you have a huge vacuum leak, or something blocking air flow. the fuel pump can also be down on pressure. leaky o rings on the injectors, but you would be able to smell fuel.
Bill,

I'm thinking you're right on the vacuum leak. We already tested fuel pressure -- 50PSI constantly. No fuel smell at all. We'll throw some pressure in the intake tomorrow and see what happens, I guess.
 

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Discussion Starter #12
Question: why would a vacuum leak only appear when I try to rev? A huge vacuum leak should cause starting and idling issues, shouldn't it?
 

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Discussion Starter #15
Update: Pumping air into it, there's no significant vacuum leaks that we can see / hear.

An additional piece of the puzzle is that we can hear what sounds like a slight backfire (a pop) through the intake if we pump the throttle while it's idling. It will also try to 'fix' timing (I think) as it almost stalls, and rev back to 1000-1200 RPM before repeating.

We think it seems like a timing issue -- any thoughts on that?
 

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Discussion Starter #18
I would check your connection's at the ckps and cps.
Along those lines, one thing that it will do is idle, drop (according to tach) to 0, rev up, repeat -- except that the engine is still obviously turning at the time. Is this normal behavior, or could the CkPS be causing that?
 

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Discussion Starter #20
throtle position sensor perhaps, crossed ig. wires. both conditons cause similar issues.
Carlos,

We swapped TPS with the one from the old (broken cam) engine, no change, and it seems to respond properly to changes. Ignition wires is possible, but I thought I made pretty sure... do you mean leads, or connectors from ECU?
 
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